diff --git a/.gitignore b/.gitignore
index cd9275db..654d5e1a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,3 +3,6 @@ node_modules
 .env
 .DS_Store
 replica.key
+deploy/dev
+!deploy/dev/docker-compose.yml
+set-env.sh
diff --git a/packages/api-server/src/admin.html b/packages/api-server/src/admin.html
index 134ed577..4a081980 100644
--- a/packages/api-server/src/admin.html
+++ b/packages/api-server/src/admin.html
@@ -79,14 +79,17 @@ <h2>Domains</h2>
 </div>
 
 <h2>Problems</h2>
+<!--
 <input type="text" id="problem-name" placeholder="name"><br>
 <input type="text" id="problem-context" placeholder="context"><br>
 <input type="text" id="problem-input" placeholder="input"><br>
 <input type="text" id="problem-output" placeholder="output"><br>
 <button id='problem-add'>add</button> <br>
+-->
 <button id='problem-polygon'>polygon add</button> (zipped package)
 <input type="file" id="problem-polygon-input"> <br>
-<button id='problem-get'>get</button> <br>
+<button id='problem-get'>get</button> 
+<button id='problem-delete'>delete</button> <br>
 
 <div id='problem-list'>
 </div>
@@ -106,13 +109,15 @@ <h2>Contests</h2>
 <input type="number" id="contest-endTime" placeholder="endTime"><br>
 <button id='contest-add'>add</button> <br>
 <button id='contest-add-problem'>add problem</button> <br>
-<button id='contest-get'>get</button> <br>
+<button id='contest-get'>get</button> 
+<button id='contest-delete'>delete</button> <br>
 
 <div id='contest-list'>
 </div>
 
 <h2>Contest Problems</h2>
-<button id='contest-problem-get'>get</button> <br>
+<button id='contest-problem-get'>get</button> 
+<button id='contest-problem-delete'>delete</button> <br>
 
 <div id='contest-problem-list'>
 </div>
@@ -121,17 +126,19 @@ <h2>Publish</h2>
 <button id='contest-publish'>publish</button>
 
 <h2>Testcases</h2>
+<!--
 <input type="file" id="testcase-input"> <br>
 <input type="file" id="testcase-output"> <br>
 <button id='testcase-upload'>upload</button>
-<button id='testcase-get'>get</button>
 <button id='testcase-delete' disabled>delete</button>
+-->
 
+<button id='testcase-get'>get</button>
 <div id='testcase-list'>
 </div>
 
 <script>
-  const uploadURL = 'http://localhost:8001';
+  const uploadURL = 'http://13.93.218.61:8001';
 
   let getUserId = _ => undefined;
 
@@ -139,6 +146,7 @@ <h2>Testcases</h2>
   const getProblemId = _ => {let e = document.querySelector('input[name="problem-radio"]:checked'); return e ? e.value : undefined;};
   const getSeriesId = _ => {let e = document.querySelector('input[name="series-radio"]:checked'); return e ? e.value : undefined;};
   const getContestId = _ => {let e = document.querySelector('input[name="contest-radio"]:checked'); return e ? e.value : undefined;};
+  const getContestProblemId = _ => {let e = document.querySelector('input[name="contest-problem-radio"]:checked'); return e ? e.value : undefined;};
   const getTestcaseId = _ => {let e = document.querySelector('input[name="testcase-radio"]:checked'); return e ? e.value : undefined;};
 
   const betterFetch = (url, options) => 
@@ -268,6 +276,7 @@ <h2>Testcases</h2>
     document.getElementById('domain-list').innerHTML = html;
   }
 
+/*
   document.getElementById('problem-add').onclick = async _ => {
 
     console.log('problem-add');
@@ -301,6 +310,17 @@ <h2>Testcases</h2>
       .then(res => console.log(res))
       .catch(console.error);
   }
+  */
+  document.getElementById('problem-delete').onclick = async _ => {
+
+    console.log('problem-delete');
+
+    if (getDomainId() === undefined) return alert('no domain selected');
+    if (getProblemId() === undefined) return alert('no problem selected');
+
+    await betterFetch(`/v1/domains/${getDomainId()}/problems/${getProblemId()}`, { method: 'DELETE' })
+      .then(_ => alert('problem deleted'))
+  }
 
   document.getElementById('problem-polygon').onclick = async _ => {
 
@@ -349,7 +369,7 @@ <h2>Testcases</h2>
           <label for='${id}'><b>${name}</b> (<i>${id}</i>)</label>
         </summary>
         ${problemHTML}
-      </div>`
+      </details>`
     }
    document.getElementById('problem-list').innerHTML = html;
   }
@@ -476,12 +496,27 @@ <h2>Testcases</h2>
 
     let html = '';
     for (const { name, id } of problems) {
-      html += `<div><b>${name}</b>: (<i>${id}</i>)</div>`
+      html += `
+      <div>
+        <input type='radio' name='contest-problem-radio' value='${id}'>
+        <b>${name}</b>: (<i>${id}</i>)
+      </div>`
     }
 
     document.getElementById('contest-problem-list').innerHTML = html;
   }
 
+  document.getElementById('contest-problem-delete').onclick = async _ => {
+
+    console.log('contest-problem-delete');
+
+    if (getContestId() === undefined) return alert('no contest selected');
+    if (getContestProblemId() === undefined) return alert('no contest problem selected');
+
+    await betterFetch(`/v1/contests/${getContestId()}/problems/${getContestProblemId()}`, { method: 'DELETE' })
+  }
+
+  /*
   document.getElementById('testcase-upload').onclick = async _ => {
 
     console.log('testcase-upload');
@@ -530,6 +565,7 @@ <h2>Testcases</h2>
     })
       .alert('testcase added')
   }
+  */
 
   document.getElementById('testcase-get').onclick = async _ => {
 
diff --git a/packages/api-server/src/client.html b/packages/api-server/src/client.html
index a2c648fe..89986357 100644
--- a/packages/api-server/src/client.html
+++ b/packages/api-server/src/client.html
@@ -283,7 +283,7 @@ <h2>Ranklist</h2>
           <label for='${id}'><b>${name}</b> (<i>${id}</i>)</label>
         </summary>
         ${problemHTML}
-      </div>`
+      </details>`
     }
 
     document.getElementById('problem-list').innerHTML = html;
@@ -327,8 +327,12 @@ <h2>Ranklist</h2>
       .then(res => res.json());
 
     let html = '';
-    for (const { problemName, problemId, createdAt, status, score, testcases, id } of submissions) {
+    for (const { problemName, problemId, createdAt, status, score, testcases, id, log } of submissions) {
       html += `<div><b>${problemName}</b> @ ${(new Date(createdAt)).toLocaleString()}: <b>${status}</b> <i>(${id})</i><br> <b>${score !== undefined ? score : '...'}</b> => `
+
+      if (log) html += `<b style='color: red'>${log}</b><br>`
+      if (status !== 'Graded') continue;
+      if (!testcases) continue;
       for (const { result } of testcases) {
         html += `${result.status}:${result.wallTime}ms <b>||</b> `
       }
diff --git a/packages/api-server/src/routes/v1/contest.routes.ts b/packages/api-server/src/routes/v1/contest.routes.ts
index 65a42b3e..e91fbda1 100644
--- a/packages/api-server/src/routes/v1/contest.routes.ts
+++ b/packages/api-server/src/routes/v1/contest.routes.ts
@@ -65,6 +65,7 @@ import { userAuthHook } from '../../hooks/authentication.hooks.js'
 import { contestInfoHook } from '../../hooks/contest.hooks.js'
 import { requestUserProfile } from '../../utils/auth.utils.js'
 import {fetchUser} from '../../services/user.services.js'
+/*=*/
 
 async function contestProblemRoutes (problemRoutes: FastifyTypeBox): Promise<void> {
   problemRoutes.addHook('onRequest', contestInfoHook)
diff --git a/packages/api-server/src/routes/v1/domain.routes.ts b/packages/api-server/src/routes/v1/domain.routes.ts
index 80417f43..35a8d3a3 100644
--- a/packages/api-server/src/routes/v1/domain.routes.ts
+++ b/packages/api-server/src/routes/v1/domain.routes.ts
@@ -21,14 +21,15 @@ import {
 } from '../../services/domain.services.js'
 import { isSuperAdmin } from '../../auth/role.auth.js'
 import { hasDomainPrivilege } from '../../auth/scope.auth.js'
-import { type FastifyTypeBox } from '../../types.js'
-import { createDomainProblem, deleteDomainProblem, fetchDomainProblems, updateDomainProblem } from '../../services/problem.services.js'
+import { type FastifyTypeBox } from '../../types.js' /*=*/
+import { deleteDomainProblem, fetchDomainProblems } from '../../services/problem.services.js'
 import { fetchDomainProblem } from '@argoncs/common'
 import { createTestingSubmission } from '../../services/submission.services.js'
-import { createPolygonUploadSession, createUploadSession } from '../../services/testcase.services.js'
+import { createPolygonUploadSession } from '../../services/testcase.services.js'
 import { UnauthorizedError, badRequestSchema, forbiddenSchema, methodNotAllowedSchema, notFoundSchema, unauthorizedSchema } from 'http-errors-enhanced'
 import { createContest, createContestSeries, fetchDomainContestSeries, fetchDomainContests } from '../../services/contest.services.js'
 import { userAuthHook } from '../../hooks/authentication.hooks.js'
+/*=*/
 
 async function domainMemberRoutes (memberRoutes: FastifyTypeBox): Promise<void> {
   memberRoutes.post(
@@ -134,6 +135,7 @@ async function domainMemberRoutes (memberRoutes: FastifyTypeBox): Promise<void>
 }
 
 async function domainProblemRoutes (problemRoutes: FastifyTypeBox): Promise<void> {
+/*
   problemRoutes.post(
     '/',
     {
@@ -158,6 +160,7 @@ async function domainProblemRoutes (problemRoutes: FastifyTypeBox): Promise<void
       return await reply.status(201).send(created)
     }
   )
+*/
 
   problemRoutes.get(
     '/',
@@ -182,6 +185,7 @@ async function domainProblemRoutes (problemRoutes: FastifyTypeBox): Promise<void
     }
   )
 
+/*
   problemRoutes.put(
     '/:problemId',
     {
@@ -207,6 +211,7 @@ async function domainProblemRoutes (problemRoutes: FastifyTypeBox): Promise<void
       return await reply.status(200).send({ modified })
     }
   )
+*/
 
   problemRoutes.delete(
     '/:problemId',
@@ -286,6 +291,7 @@ async function domainProblemRoutes (problemRoutes: FastifyTypeBox): Promise<void
     }
   )
 
+/*
   problemRoutes.get(
     '/:problemId/upload-session',
     {
@@ -309,6 +315,7 @@ async function domainProblemRoutes (problemRoutes: FastifyTypeBox): Promise<void
       await reply.status(200).send({ uploadId })
     }
   )
+*/
 
   problemRoutes.get(
     '/polygon-upload-session',
diff --git a/packages/api-server/src/routes/v1/user.routes.ts b/packages/api-server/src/routes/v1/user.routes.ts
index 30b87531..7176e33e 100644
--- a/packages/api-server/src/routes/v1/user.routes.ts
+++ b/packages/api-server/src/routes/v1/user.routes.ts
@@ -126,7 +126,8 @@ async function userSubmissionRoutes (submissionRoutes: FastifyTypeBox): Promise<
           ])),
           400: badRequestSchema,
           401: unauthorizedSchema,
-          403: forbiddenSchema
+          403: forbiddenSchema,
+          404: notFoundSchema
         }
       },
       onRequest: [userAuthHook, submissionRoutes.auth([
diff --git a/packages/api-server/src/services/problem.services.ts b/packages/api-server/src/services/problem.services.ts
index 66fffc3c..8eb08551 100644
--- a/packages/api-server/src/services/problem.services.ts
+++ b/packages/api-server/src/services/problem.services.ts
@@ -8,19 +8,22 @@ import { testcaseExists } from './testcase.services.js'
 
 import { nanoid } from 'nanoid'
 
+/*
 export async function createDomainProblem ({ newProblem, domainId }: { newProblem: NewProblem, domainId: string }): Promise<{ problemId: string }> {
   const problemId = nanoid()
   const problem: Problem = { ...newProblem, id: problemId, domainId }
   await domainProblemCollection.insertOne(problem)
   return { problemId }
 }
+*/
 
+/*
 export async function updateDomainProblem ({ problemId, domainId, problem }: { problemId: string, domainId: string, problem: Partial<NewProblem> }): Promise<{ modified: boolean }> {
   if (problem.testcases != null) {
     const testcasesVerifyQueue: Array<Promise<void>> = []
     problem.testcases.forEach((testcase) => {
-      testcasesVerifyQueue.push(testcaseExists({ problemId, domainId, filename: testcase.input.name, versionId: testcase.input.versionId }))
-      testcasesVerifyQueue.push(testcaseExists({ problemId, domainId, filename: testcase.output.name, versionId: testcase.output.versionId }))
+      testcasesVerifyQueue.push(testcaseExists({ problemId, filename: testcase.input.name, versionId: testcase.input.versionId }))
+      testcasesVerifyQueue.push(testcaseExists({ problemId, filename: testcase.output.name, versionId: testcase.output.versionId }))
     })
     await Promise.all(testcasesVerifyQueue)
   }
@@ -32,6 +35,7 @@ export async function updateDomainProblem ({ problemId, domainId, problem }: { p
 
   return { modified: modifiedCount > 0 }
 }
+*/
 
 export async function deleteDomainProblem ({ problemId, domainId }: { problemId: string, domainId: string }): Promise<void> {
   const session = mongoClient.startSession()
diff --git a/packages/api-server/src/services/submission.services.ts b/packages/api-server/src/services/submission.services.ts
index 586b603b..f8cfdc16 100644
--- a/packages/api-server/src/services/submission.services.ts
+++ b/packages/api-server/src/services/submission.services.ts
@@ -5,7 +5,7 @@ import {
   SubmissionStatus,
   type Submission,
   type Problem
-} from '@argoncs/types'
+} from '@argoncs/types' /*=*/
 import { rabbitMQ, judgerExchange, judgerTasksKey, submissionCollection, fetchDomainProblem, fetchContestProblem } from '@argoncs/common'
 import { languageConfigs } from '../../configs/language.configs.js'
 
diff --git a/packages/api-server/src/services/testcase.services.ts b/packages/api-server/src/services/testcase.services.ts
index b5a80598..f826f193 100644
--- a/packages/api-server/src/services/testcase.services.ts
+++ b/packages/api-server/src/services/testcase.services.ts
@@ -4,10 +4,9 @@ import { fetchDomainProblem, minio, uploadSessionCollection } from '@argoncs/com
 import path = require('node:path')
 import { nanoid } from 'nanoid'
 
-export async function testcaseExists ({ problemId, domainId, filename, versionId }: { problemId: string, domainId: string, filename: string, versionId: string }): Promise<void> {
-  const objectName = path.join(domainId, problemId, filename)
+export async function testcaseExists ({ problemId, filename, versionId }: { problemId: string, filename: string, versionId: string }): Promise<void> {
   try {
-    const stat = await minio.statObject('testcases', objectName, { versionId })
+    const stat = await minio.statObject('testcases', path.join(problemId, filename), { versionId })
 
     if (stat == null || stat.versionId !== versionId) {
       throw new NotFoundError('One of the testcases not found')
@@ -17,12 +16,14 @@ export async function testcaseExists ({ problemId, domainId, filename, versionId
   }
 }
 
+/*
 export async function createUploadSession ({ problemId, domainId }: { problemId: string, domainId: string }): Promise<{ uploadId: string }> {
   const id = nanoid(32)
   await fetchDomainProblem({ problemId, domainId }) // Could throw not found
   await uploadSessionCollection.insertOne({ id, problemId, domainId, createdAt: (new Date()).getTime() })
   return { uploadId: id }
 }
+*/
 
 export async function createPolygonUploadSession ({ domainId }: { domainId: string }): Promise<{ uploadId: string }> {
   const id = nanoid(32)
diff --git a/packages/common/src/connections/minio.connections.ts b/packages/common/src/connections/minio.connections.ts
index f76e6e08..e483aa89 100644
--- a/packages/common/src/connections/minio.connections.ts
+++ b/packages/common/src/connections/minio.connections.ts
@@ -34,7 +34,11 @@ export async function connectMinIO (url: string): Promise<void> {
   if (!await minio.bucketExists('binaries')) {
     await minio.makeBucket('binaries')
   }
+  if (!await minio.bucketExists('checkers')) {
+    await minio.makeBucket('checkers')
+  }
   await minio.setBucketVersioning('testcases', { Status: 'Enabled' })
+  await minio.setBucketVersioning('checkers', { Status: 'Enabled' })
 }
 
 export { minio }
diff --git a/packages/judge-daemon/.gitignore b/packages/judge-daemon/.gitignore
index 76add878..d8ac1ef6 100644
--- a/packages/judge-daemon/.gitignore
+++ b/packages/judge-daemon/.gitignore
@@ -1,2 +1,4 @@
 node_modules
-dist
\ No newline at end of file
+dist
+box-metas
+argon-cache
diff --git a/packages/judge-daemon/src/services/compile.services.ts b/packages/judge-daemon/src/services/compile.services.ts
index 0fad2f36..8e67b2c0 100644
--- a/packages/judge-daemon/src/services/compile.services.ts
+++ b/packages/judge-daemon/src/services/compile.services.ts
@@ -3,24 +3,22 @@ import { promises as fs } from 'node:fs'
 
 import { runInSandbox } from './sandbox.services.js'
 
-import { type CompilingTask, SandboxStatus, type CompileSucceeded, type CompileFailed, CompilingStatus } from '@argoncs/types'
+import { type CompilingTask, SandboxStatus, type CompileSucceeded, type CompileFailed, CompilingStatus, type CompilingCheckerTask, CompilingCheckerResult } from '@argoncs/types'
 import { minio } from '@argoncs/common'
 import { languageConfigs } from '../../configs/language.configs.js'
 
-//=
+/*=*/
+
 export async function compileSubmission ({ task, boxId }: { task: CompilingTask, boxId: number }): Promise<CompileSucceeded | CompileFailed> {
   const workDir = `/var/local/lib/isolate/${boxId}/box`
   const config = languageConfigs[task.language]
   const srcPath = path.join(workDir, config.srcFile)
   const binaryPath = path.join(workDir, config.binaryFile)
-  const logPath = path.join(workDir, 'log.txt')
   await fs.writeFile(srcPath, task.source)
-  let command = config.compileCommand
-  command = command.replaceAll('{src_path}', config.srcFile)
-  command = command.replaceAll('{binary_path}', config.binaryFile)
 
-  console.log('command:', command);
-  console.log(workDir, config, srcPath, binaryPath, logPath);
+  const command = config.compileCommand
+    .replaceAll('{src_path}', config.srcFile)
+    .replaceAll('{binary_path}', config.binaryFile)
 
   const result = await runInSandbox(
     {
@@ -40,10 +38,61 @@ export async function compileSubmission ({ task, boxId }: { task: CompilingTask,
       status: CompilingStatus.Succeeded
     }
   } else {
-    const log = (await fs.readFile(logPath)).toString()
+    const log = (await fs.readFile(path.join(workDir, 'log.txt'))).toString()
     return {
       status: CompilingStatus.Failed,
       log
     }
   }
 }
+
+export async function compileChecker ({ task, boxId }: { task: CompilingCheckerTask, boxId: number }): Promise<CompilingCheckerResult>
+{
+  const workDir = `/var/local/lib/isolate/${boxId}/box`
+  const srcPath = path.join(workDir, 'checker.cpp')
+  const binaryPath = path.join(workDir, 'checker')
+  await fs.writeFile(srcPath, task.source);
+  await fs.copyFile('testlib.h', path.join(workDir, 'testlib.h'))
+
+  const command = '/usr/bin/g++ -o2 -w -fmax-errors=3 -std=c++17 checker.cpp -lm -o checker' 
+
+  const result = await runInSandbox({
+    task: {
+      constraints: {
+        processes: 5,
+        memory: 262144,
+        totalStorage: 262144,
+      },
+      command,
+      stderrPath: 'log.txt',
+      env: 'PATH=/bin:/usr/local/bin:/usr/bin'
+    },
+    boxId
+  })
+
+  console.log('compiled checker')
+
+  if (result.status !== SandboxStatus.Succeeded)
+    return {
+      status: CompilingStatus.Failed,
+      log: (await fs.readFile(path.join(workDir, 'log.txt'))).toString()
+    }
+  
+  const { versionId } = await minio.putObject('checkers', task.problemId, (await fs.open(binaryPath)).createReadStream())
+
+  if (versionId === null) 
+    return {
+      status: CompilingStatus.Failed,
+      log: 'failed to put into bucket'
+    }
+
+  console.log("checker inserted")
+
+  return {
+    status: CompilingStatus.Succeeded,
+    checker: {
+      name: task.problemId,
+      versionId
+    }
+  }
+}
diff --git a/packages/judge-daemon/src/services/grading.services.ts b/packages/judge-daemon/src/services/grading.services.ts
index 719d13c5..d811f5ff 100644
--- a/packages/judge-daemon/src/services/grading.services.ts
+++ b/packages/judge-daemon/src/services/grading.services.ts
@@ -8,8 +8,8 @@ import { makeExecutable, exec } from '../utils/system.utils.js'
 import {
   runInSandbox
 } from './sandbox.services.js'
-
-import { fetchBinary, fetchTestcase } from './storage.services.js'
+import { promises as fs } from 'node:fs'
+import { fetchBinary, fetchTestcase, fetchChecker } from './storage.services.js'
 
 export async function gradeSubmission ({ task, boxId }: { task: GradingTask, boxId: number }): Promise<GradingResult> {
 
@@ -17,12 +17,17 @@ export async function gradeSubmission ({ task, boxId }: { task: GradingTask, box
   const config = languageConfigs[task.language]
   const binaryPath = path.join(workDir, config.binaryFile)
   const inputPath = path.join(workDir, 'in.txt')
+  const outputPath = path.join(workDir, 'out.txt');
   const answerPath = path.join(workDir, 'ans.txt')
+  const checkerPath = path.join(workDir, 'checker');
+  const verdictPath = path.join(workDir, 'verdict.txt');
 
   await fetchBinary({ objectName: task.submissionId, destPath: binaryPath })
   await fetchTestcase({ objectName: task.testcase.input.objectName, versionId: task.testcase.input.versionId, destPath: inputPath })
   await fetchTestcase({ objectName: task.testcase.output.objectName, versionId: task.testcase.output.versionId, destPath: answerPath })
-  await makeExecutable(path.join(workDir, config.binaryFile))
+  await fetchChecker({ objectName: task.checker.objectName, versionId: task.checker.versionId, destPath: checkerPath })
+  await makeExecutable(binaryPath)
+  await makeExecutable(checkerPath)
 
   let command = config.executeCommand
   command = command.replaceAll('{binary_path}', config.binaryFile)
@@ -38,29 +43,53 @@ export async function gradeSubmission ({ task, boxId }: { task: GradingTask, box
       },
       boxId
     })
+
   //return  new Promise((resolve, reject) => resolve({ message: '', status: GradingStatus.Accepted, memory: 1, time: 1, wallTime: 1}));
   
-  if (sandboxResult.status === SandboxStatus.Succeeded) {
-    const { time, wallTime, memory } = sandboxResult
-    try {
-      await exec(`diff -Z -B ${answerPath} ${path.join(workDir, 'out.txt')}`)
-      return {
-        status: GradingStatus.Accepted,
-        time,
-        wallTime,
-        memory,
-        message: 'Submission accepted'
-      }
-    } catch (err) {
-      return {
-        status: GradingStatus.WrongAnswer,
-        time,
-        wallTime,
-        memory,
-        message: 'Wrong answer'
-      }
-    }
-  } else {
+  if (sandboxResult.status !== SandboxStatus.Succeeded) 
     return sandboxResult
+
+  const { time, wallTime, memory } = sandboxResult
+  try {
+    const command = `./checker in.txt ans.txt out.txt`;
+    const result = await runInSandbox(
+    {
+      task: {
+        command,
+        constraints: {
+          processes: 5,
+          memory: 262144,
+          totalStorage: 262144,
+        },
+        stderrPath: 'verdict.txt' 
+      },
+      boxId
+    })
+
+    if (result.status !== SandboxStatus.Succeeded) 
+      throw result
+
+    const verdict = (await fs.readFile(verdictPath)).toString()
+    const passed = verdict.startsWith('ok');
+
+    console.log('checker: ', command);
+    console.log('verdict: ', passed);
+    return {
+      status: passed ? GradingStatus.Accepted : GradingStatus.WrongAnswer,
+      time,
+      wallTime,
+      memory,
+      message: passed ? 'Submission accepted' : 'Wrong answer'
+    }
+  } catch (err) {
+
+    console.log('checker failed', err)
+    return {
+      status: GradingStatus.WrongAnswer,
+      time,
+      wallTime,
+      memory,
+      message: `Checker failed with: ${JSON.stringify(err)}`
+    }
   }
 }
diff --git a/packages/judge-daemon/src/services/sandbox.services.ts b/packages/judge-daemon/src/services/sandbox.services.ts
index 88de49ac..c84828aa 100644
--- a/packages/judge-daemon/src/services/sandbox.services.ts
+++ b/packages/judge-daemon/src/services/sandbox.services.ts
@@ -88,10 +88,9 @@ interface SandboxSucceeded {
   wallTime: number
 }
 
-export async function runInSandbox (
-  { task, boxId }: { task: SandboxTask, boxId: number }): Promise<
-  SandboxSucceeded | SandboxMemoryExceeded | SandboxSystemError | SandboxTimeExceeded | SandboxRuntimeError
-  > {
+export async function runInSandbox ({ task, boxId }: { task: SandboxTask, boxId: number }):
+  Promise<SandboxSucceeded | SandboxMemoryExceeded | SandboxSystemError | SandboxTimeExceeded | SandboxRuntimeError> 
+{
   let command = `isolate --run --cg --box-id=${boxId} --meta=${metaPath(boxId)}`
 
   if (task.constraints.memory != null) {
diff --git a/packages/judge-daemon/src/services/storage.services.ts b/packages/judge-daemon/src/services/storage.services.ts
index 76e662b4..c099875c 100644
--- a/packages/judge-daemon/src/services/storage.services.ts
+++ b/packages/judge-daemon/src/services/storage.services.ts
@@ -73,3 +73,37 @@ export async function fetchBinary ({ objectName, destPath }: { objectName: strin
     await fs.copyFile(key, destPath)
   }
 }
+
+async function cacheChecker ({ objectName, versionId }: { objectName: string, versionId: string }): Promise<void> {
+  // TODO: try catch. checker may not exist, throw something.
+  try {
+    const key = path.join(cacheDir, 'checkers', objectName)
+    const size = (await minio.statObject('checkers', objectName, { versionId })).size
+
+    // @ts-expect-error typing bug
+    await minio.fGetObject('checkers', objectName, key, { versionId })
+    cache.set(key, key, { size })
+
+  } catch (err) {
+    console.log('cache checker error:', err)
+    throw "none such checker"
+  }
+}
+
+export async function fetchChecker ({ objectName, versionId, destPath }: { objectName: string, versionId: string, destPath: string }): Promise<void> {
+  const key = path.join(cacheDir, 'checkers', objectName)
+  if (cache.get(key) != null) {
+    await fs.copyFile(key, destPath); return
+  }
+  if (downloading.get(key) != null) {
+    await downloading.get(key)
+    if (cache.get(key) != null) {
+      await fs.copyFile(key, destPath)
+    }
+  } else {
+    downloading.set(key, cacheChecker({ objectName, versionId }))
+    await downloading.get(key)
+    downloading.delete(key)
+    await fs.copyFile(key, destPath)
+  }
+}
diff --git a/packages/judge-daemon/src/start.ts b/packages/judge-daemon/src/start.ts
index 77d414a0..39a6ad93 100644
--- a/packages/judge-daemon/src/start.ts
+++ b/packages/judge-daemon/src/start.ts
@@ -1,8 +1,8 @@
 import { destroySandbox, initSandbox } from './services/sandbox.services.js'
 import { gradeSubmission } from './services/grading.services.js'
-import { compileSubmission } from './services/compile.services.js'
+import { compileChecker, compileSubmission } from './services/compile.services.js'
 
-import { type GradingTask, type CompilingTask, JudgerTaskType, type GradingResultMessage, JudgerResultType, type CompilingResultMessage } from '@argoncs/types'
+import { type GradingTask, type CompilingTask, JudgerTaskType, type GradingResultMessage, JudgerResultType, type CompilingResultMessage, CompilingCheckerTask, CompilingCheckerResultMessage } from '@argoncs/types'
 import { rabbitMQ, judgerTasksQueue, judgerExchange, judgerResultsKey, sentry, connectRabbitMQ, connectMinIO } from '@argoncs/common'
 
 import os = require('node:os')
@@ -22,10 +22,12 @@ sentry.init({
   release: process.env.npm_package_version
 })
 
-export async function startJudger (): Promise<void> {
+export async function startJudger (): Promise<void> 
+{
   assert(process.env.RABBITMQ_URL != null)
-  await connectRabbitMQ(process.env.RABBITMQ_URL)
   assert(process.env.MINIO_URL != null)
+
+  await connectRabbitMQ(process.env.RABBITMQ_URL)
   await connectMinIO(process.env.MINIO_URL)
 
   console.log('CWD: ', process.cwd()); 
@@ -36,8 +38,7 @@ export async function startJudger (): Promise<void> {
   logger.info(`${cores} CPU cores detected`)
 
   const destroyQueue: Array<Promise<{ boxId: number }>> = []
-  for (let id = 1; id <= cores; id += 1) {
-    console.log('delete old box')
+  for (let id = 1; id <= cores; id ++) {
     destroyQueue.push(destroySandbox({ boxId: id }))
     availableBoxes.add(id)
   }
@@ -46,64 +47,68 @@ export async function startJudger (): Promise<void> {
   logger.info(`Judger ${judgerId} start receiving tasks`)
 
   await rabbitMQ.prefetch(availableBoxes.size)
+
   // eslint-disable-next-line @typescript-eslint/no-misused-promises
   await rabbitMQ.consume(judgerTasksQueue, async (message) => {
-    console.log('hi');
-    if (message != null) {
-      const boxId = availableBoxes.values().next().value
-      if (boxId == null) {
-        rabbitMQ.reject(message, true)
-        logger.info('Received a task when no box is available')
-        return
-      }
-      try {
-        const task: GradingTask | CompilingTask = JSON.parse(message.content.toString())
-
-        console.log('start task')
-        logger.info(task, 'Processing a new task')
-        availableBoxes.delete(boxId)
-        await initSandbox({ boxId })
-
-        let result: CompilingResultMessage | GradingResultMessage
-
-        if (task.type === JudgerTaskType.Grading) {
-          console.log('grading')
-          result = {
-            type: JudgerResultType.Grading,
-            result: (await gradeSubmission({ task, boxId })),
-            submissionId: task.submissionId,
-            testcaseIndex: task.testcaseIndex
-          }
-          // send grade message
-        } else if (task.type === JudgerTaskType.Compiling) {
-          console.log('compiling')
-          result = {
-            type: JudgerResultType.Compiling,
-            result: (await compileSubmission({ task, boxId })),
-            submissionId: task.submissionId
-          }
-
-          // send grade message
-        } else {
-          throw Error('Invalid task type')
-        }
+    if (message == null) return;
 
-        rabbitMQ.publish(judgerExchange, judgerResultsKey, Buffer.from(JSON.stringify(result)))
+    const boxId = availableBoxes.values().next().value
 
-        console.log('done task')
-        //await destroySandbox({ boxId })
-        availableBoxes.add(boxId)
+    if (boxId == null) {
+      rabbitMQ.reject(message, true)
+      logger.info('Received a task when no box is available')
+      return
+    }
 
-        rabbitMQ.ack(message)
-      } catch (err) {
-        sentry.captureException(err)
+    try {
+      const task: GradingTask | CompilingTask | CompilingCheckerTask = JSON.parse(message.content.toString())
 
-        console.log('task failed', err)
-        await destroySandbox({ boxId })
-        availableBoxes.add(boxId)
+      logger.info(task, `Processing a new task: ${task}`)
+      availableBoxes.delete(boxId)
+      await initSandbox({ boxId })
 
-        rabbitMQ.reject(message, false)
+      if (task.type === JudgerTaskType.CompilingChecker) {
+        const result: CompilingCheckerResultMessage = {
+          type: JudgerResultType.CompilingChecker,
+          result: await compileChecker({ task, boxId }),
+          problemId: task.problemId,
+        }
+        rabbitMQ.publish(judgerExchange, judgerResultsKey, Buffer.from(JSON.stringify(result)))
+      } else 
+      if (task.type === JudgerTaskType.Grading) {
+        const result: GradingResultMessage = {
+          type: JudgerResultType.Grading,
+          result: await gradeSubmission({ task, boxId }),
+          submissionId: task.submissionId,
+          testcaseIndex: task.testcaseIndex
+        }
+        rabbitMQ.publish(judgerExchange, judgerResultsKey, Buffer.from(JSON.stringify(result)))
+      } else 
+      if (task.type === JudgerTaskType.Compiling) {
+        const result: CompilingResultMessage = {
+          type: JudgerResultType.Compiling,
+          result: await compileSubmission({ task, boxId }),
+          submissionId: task.submissionId
+        }
+        rabbitMQ.publish(judgerExchange, judgerResultsKey, Buffer.from(JSON.stringify(result)))
+      } else {
+        throw Error('Invalid task type')
       }
+
+      console.log('done task')
+      // NOTE: temporary
+      // await destroySandbox({ boxId })
+      availableBoxes.add(boxId)
+      rabbitMQ.ack(message)
+
+    } catch (err) {
+      sentry.captureException(err)
+
+      console.log('task failed')
+      //await destroySandbox({ boxId })
+      availableBoxes.add(boxId)
+
+      rabbitMQ.reject(message, false)
     }
   })
 }
diff --git a/packages/judge-daemon/testlib.h b/packages/judge-daemon/testlib.h
new file mode 100644
index 00000000..4e1d3682
--- /dev/null
+++ b/packages/judge-daemon/testlib.h
@@ -0,0 +1,6299 @@
+/*
+ * It is strictly recommended to include "testlib.h" before any other include
+ * in your code. In this case testlib overrides compiler specific "random()".
+ *
+ * If you can't compile your code and compiler outputs something about
+ * ambiguous call of "random_shuffle", "rand" or "srand" it means that
+ * you shouldn't use them. Use "shuffle", and "rnd.next()" instead of them
+ * because these calls produce stable result for any C++ compiler. Read
+ * sample generator sources for clarification.
+ *
+ * Please read the documentation for class "random_t" and use "rnd" instance in
+ * generators. Probably, these sample calls will be useful for you:
+ *              rnd.next(); rnd.next(100); rnd.next(1, 2);
+ *              rnd.next(3.14); rnd.next("[a-z]{1,100}").
+ *
+ * Also read about wnext() to generate off-center random distribution.
+ *
+ * See https://github.com/MikeMirzayanov/testlib/ to get latest version or bug tracker.
+ */
+
+#ifndef _TESTLIB_H_
+#define _TESTLIB_H_
+
+/*
+ * Copyright (c) 2005-2024
+ */
+
+#define VERSION "0.9.44"
+
+/*
+ * Mike Mirzayanov
+ *
+ * This material is provided "as is", with absolutely no warranty expressed
+ * or implied. Any use is at your own risk.
+ *
+ * Permission to use or copy this software for any purpose is hereby granted
+ * without fee, provided the above notices are retained on all copies.
+ * Permission to modify the code and to distribute modified code is granted,
+ * provided the above notices are retained, and a notice that the code was
+ * modified is included with the above copyright notice.
+ *
+ */
+
+/* NOTE: This file contains testlib library for C++.
+ *
+ *   Check, using testlib running format:
+ *     check.exe <Input_File> <Output_File> <Answer_File> [<Result_File> [-appes]],
+ *   If result file is specified it will contain results.
+ *
+ *   Validator, using testlib running format:
+ *     validator.exe < input.txt,
+ *   It will return non-zero exit code and writes message to standard output.
+ *
+ *   Generator, using testlib running format:
+ *     gen.exe [parameter-1] [parameter-2] [... paramerter-n]
+ *   You can write generated test(s) into standard output or into the file(s).
+ *
+ *   Interactor, using testlib running format:
+ *     interactor.exe <Input_File> <Output_File> [<Answer_File> [<Result_File> [-appes]]],
+ *   Reads test from inf (mapped to args[1]), writes result to tout (mapped to argv[2],
+ *   can be judged by checker later), reads program output from ouf (mapped to stdin),
+ *   writes output to program via stdout (use cout, printf, etc).
+ */
+
+const char *latestFeatures[] = {
+        "Added ConstantBoundsLog, VariablesLog to validator testOverviewLogFile",
+        "Use setAppesModeEncoding to change xml encoding from windows-1251 to other",
+        "rnd.any/wany use distance/advance instead of -/+: now they support sets/multisets",
+        "Use syntax `int t = inf.readInt(1, 3, \"~t\");` to skip the lower bound check. Tildes can be used on either side or both: ~t, t~, ~t~",
+        "Supported EJUDGE support in registerTestlibCmd",
+        "Supported '--testMarkupFileName fn' and '--testCase tc/--testCaseFileName fn' for validators",
+        "Added opt defaults via opt<T>(key/index, default_val); check unused opts when using has_opt or default opt (turn off this check with suppressEnsureNoUnusedOpt()).",
+        "For checker added --group and --testset command line params (like for validator), use checker.group() or checker.testset() to get values",
+        "Added quitpi(points_info, message) function to return with _points exit code 7 and given points_info",
+        "rnd.partition(size, sum[, min_part=1]) returns random (unsorted) partition which is a representation of the given `sum` as a sum of `size` positive integers (or >=min_part if specified)",
+        "rnd.distinct(size, n) and rnd.distinct(size, from, to)",
+        "opt<bool>(\"some_missing_key\") returns false now",
+        "has_opt(key)",
+        "Abort validator on validator.testset()/validator.group() if registered without using command line",
+        "Print integer range violations in a human readable way like `violates the range [1, 10^9]`",
+        "Opts supported: use them like n = opt<int>(\"n\"), in a command line you can use an exponential notation",
+        "Reformatted",
+        "Use setTestCase(i) or unsetTestCase() to support test cases (you can use it in any type of program: generator, interactor, validator or checker)",
+        "Fixed issue #87: readStrictDouble accepts \"-0.00\"",
+        "Fixed issue #83: added InStream::quitif(condition, ...)",
+        "Fixed issue #79: fixed missed guard against repeated header include",
+        "Fixed issue #80: fixed UB in case of huge quitf message",
+        "Fixed issue #84: added readXs(size, indexBase = 1)",
+        "Fixed stringstream repeated usage issue",
+        "Fixed compilation in g++ (for std=c++03)",
+        "Batch of println functions (support collections, iterator ranges)",
+        "Introduced rnd.perm(size, first = 0) to generate a `first`-indexed permutation",
+        "Allow any whitespace in readInts-like functions for non-validators",
+        "Ignore 4+ command line arguments ifdef EJUDGE",
+        "Speed up of vtos",
+        "Show line number in validators in case of incorrect format",
+        "Truncate huge checker/validator/interactor message",
+        "Fixed issue with readTokenTo of very long tokens, now aborts with _pe/_fail depending of a stream type",
+        "Introduced InStream::ensure/ensuref checking a condition, returns wa/fail depending of a stream type",
+        "Fixed compilation in VS 2015+",
+        "Introduced space-separated read functions: readWords/readTokens, multilines read functions: readStrings/readLines",
+        "Introduced space-separated read functions: readInts/readIntegers/readLongs/readUnsignedLongs/readDoubles/readReals/readStrictDoubles/readStrictReals",
+        "Introduced split/tokenize functions to separate string by given char",
+        "Introduced InStream::readUnsignedLong and InStream::readLong with unsigned long long parameters",
+        "Supported --testOverviewLogFileName for validator: bounds hits + features",
+        "Fixed UB (sequence points) in random_t",
+        "POINTS_EXIT_CODE returned back to 7 (instead of 0)",
+        "Removed disable buffers for interactive problems, because it works unexpectedly in wine",
+        "InStream over string: constructor of InStream from base InStream to inherit policies and std::string",
+        "Added expectedButFound quit function, examples: expectedButFound(_wa, 10, 20), expectedButFound(_fail, ja, pa, \"[n=%d,m=%d]\", n, m)",
+        "Fixed incorrect interval parsing in patterns",
+        "Use registerGen(argc, argv, 1) to develop new generator, use registerGen(argc, argv, 0) to compile old generators (originally created for testlib under 0.8.7)",
+        "Introduced disableFinalizeGuard() to switch off finalization checkings",
+        "Use join() functions to format a range of items as a single string (separated by spaces or other separators)",
+        "Use -DENABLE_UNEXPECTED_EOF to enable special exit code (by default, 8) in case of unexpected eof. It is good idea to use it in interactors",
+        "Use -DUSE_RND_AS_BEFORE_087 to compile in compatibility mode with random behavior of versions before 0.8.7",
+        "Fixed bug with nan in stringToDouble",
+        "Fixed issue around overloads for size_t on x64",
+        "Added attribute 'points' to the XML output in case of result=_points",
+        "Exit codes can be customized via macros, e.g. -DPE_EXIT_CODE=14",
+        "Introduced InStream function readWordTo/readTokenTo/readStringTo/readLineTo for faster reading",
+        "Introduced global functions: format(), englishEnding(), upperCase(), lowerCase(), compress()",
+        "Manual buffer in InStreams, some IO speed improvements",
+        "Introduced quitif(bool, const char* pattern, ...) which delegates to quitf() in case of first argument is true",
+        "Introduced guard against missed quitf() in checker or readEof() in validators",
+        "Supported readStrictReal/readStrictDouble - to use in validators to check strictly float numbers",
+        "Supported registerInteraction(argc, argv)",
+        "Print checker message to the stderr instead of stdout",
+        "Supported TResult _points to output calculated score, use quitp(...) functions",
+        "Fixed to be compilable on Mac",
+        "PC_BASE_EXIT_CODE=50 in case of defined TESTSYS",
+        "Fixed issues 19-21, added __attribute__ format printf",
+        "Some bug fixes",
+        "ouf.readInt(1, 100) and similar calls return WA",
+        "Modified random_t to avoid integer overflow",
+        "Truncated checker output [patch by Stepan Gatilov]",
+        "Renamed class random -> class random_t",
+        "Supported name parameter for read-and-validation methods, like readInt(1, 2, \"n\")",
+        "Fixed bug in readDouble()",
+        "Improved ensuref(), fixed nextLine to work in case of EOF, added startTest()",
+        "Supported \"partially correct\", example: quitf(_pc(13), \"result=%d\", result)",
+        "Added shuffle(begin, end), use it instead of random_shuffle(begin, end)",
+        "Added readLine(const string& ptrn), fixed the logic of readLine() in the validation mode",
+        "Package extended with samples of generators and validators",
+        "Written the documentation for classes and public methods in testlib.h",
+        "Implemented random routine to support generators, use registerGen() to switch it on",
+        "Implemented strict mode to validate tests, use registerValidation() to switch it on",
+        "Now ncmp.cpp and wcmp.cpp are return WA if answer is suffix or prefix of the output",
+        "Added InStream::readLong() and removed InStream::readLongint()",
+        "Now no footer added to each report by default (use directive FOOTER to switch on)",
+        "Now every checker has a name, use setName(const char* format, ...) to set it",
+        "Now it is compatible with TTS (by Kittens Computing)",
+        "Added \'ensure(condition, message = \"\")\' feature, it works like assert()",
+        "Fixed compatibility with MS C++ 7.1",
+        "Added footer with exit code information",
+        "Added compatibility with EJUDGE (compile with EJUDGE directive)",
+        "Added compatibility with Contester (compile with CONTESTER directive)"
+};
+
+#ifdef _MSC_VER
+#define _CRT_SECURE_NO_DEPRECATE
+#define _CRT_SECURE_NO_WARNINGS
+#define _CRT_NO_VA_START_VALIDATION
+#endif
+
+/* Overrides random() for Borland C++. */
+#define random __random_deprecated
+#include <stdlib.h>
+#include <cstdlib>
+#include <climits>
+#include <algorithm>
+#undef random
+
+#include <cstdio>
+#include <cctype>
+#include <string>
+#include <vector>
+#include <map>
+#include <set>
+#include <cmath>
+#include <iterator>
+#include <iostream>
+#include <sstream>
+#include <fstream>
+#include <cstring>
+#include <limits>
+#include <stdarg.h>
+#include <fcntl.h>
+#include <functional>
+#include <cstdint>
+
+#ifdef TESTLIB_THROW_EXIT_EXCEPTION_INSTEAD_OF_EXIT
+#   include <exception>
+#endif
+
+#if (_WIN32 || __WIN32__ || __WIN32 || _WIN64 || __WIN64__ || __WIN64 || WINNT || __WINNT || __WINNT__ || __CYGWIN__)
+#   if !defined(_MSC_VER) || _MSC_VER > 1400
+#       define NOMINMAX 1
+#       include <windows.h>
+#   else
+#       define WORD unsigned short
+#       include <unistd.h>
+#   endif
+#   include <io.h>
+#   define ON_WINDOWS
+#   if defined(_MSC_VER) && _MSC_VER > 1400
+#       pragma warning( disable : 4127 )
+#       pragma warning( disable : 4146 )
+#       pragma warning( disable : 4458 )
+#   endif
+#else
+#   define WORD unsigned short
+#   include <unistd.h>
+#endif
+
+#if defined(FOR_WINDOWS) && defined(FOR_LINUX)
+#error Only one target system is allowed
+#endif
+
+#ifndef LLONG_MIN
+#define LLONG_MIN   (-9223372036854775807LL - 1)
+#endif
+
+#ifndef ULLONG_MAX
+#define ULLONG_MAX   (18446744073709551615)
+#endif
+
+#define LF ((char)10)
+#define CR ((char)13)
+#define TAB ((char)9)
+#define SPACE ((char)' ')
+#define EOFC (255)
+
+#ifndef OK_EXIT_CODE
+#   ifdef CONTESTER
+#       define OK_EXIT_CODE 0xAC
+#   else
+#       define OK_EXIT_CODE 0
+#   endif
+#endif
+
+#ifndef WA_EXIT_CODE
+#   ifdef EJUDGE
+#       define WA_EXIT_CODE 5
+#   elif defined(CONTESTER)
+#       define WA_EXIT_CODE 0xAB
+#   else
+#       define WA_EXIT_CODE 1
+#   endif
+#endif
+
+#ifndef PE_EXIT_CODE
+#   ifdef EJUDGE
+#       define PE_EXIT_CODE 4
+#   elif defined(CONTESTER)
+#       define PE_EXIT_CODE 0xAA
+#   else
+#       define PE_EXIT_CODE 2
+#   endif
+#endif
+
+#ifndef FAIL_EXIT_CODE
+#   ifdef EJUDGE
+#       define FAIL_EXIT_CODE 6
+#   elif defined(CONTESTER)
+#       define FAIL_EXIT_CODE 0xA3
+#   else
+#       define FAIL_EXIT_CODE 3
+#   endif
+#endif
+
+#ifndef DIRT_EXIT_CODE
+#   ifdef EJUDGE
+#       define DIRT_EXIT_CODE 6
+#   else
+#       define DIRT_EXIT_CODE 4
+#   endif
+#endif
+
+#ifndef POINTS_EXIT_CODE
+#   define POINTS_EXIT_CODE 7
+#endif
+
+#ifndef UNEXPECTED_EOF_EXIT_CODE
+#   define UNEXPECTED_EOF_EXIT_CODE 8
+#endif
+
+#ifndef PC_BASE_EXIT_CODE
+#   ifdef TESTSYS
+#       define PC_BASE_EXIT_CODE 50
+#   else
+#       define PC_BASE_EXIT_CODE 0
+#   endif
+#endif
+
+#ifdef __GNUC__
+#    define __TESTLIB_STATIC_ASSERT(condition) typedef void* __testlib_static_assert_type[(condition) ? 1 : -1] __attribute__((unused))
+#else
+#    define __TESTLIB_STATIC_ASSERT(condition) typedef void* __testlib_static_assert_type[(condition) ? 1 : -1]
+#endif
+
+#ifdef ON_WINDOWS
+#define I64 "%I64d"
+#define U64 "%I64u"
+#else
+#define I64 "%lld"
+#define U64 "%llu"
+#endif
+
+#ifdef _MSC_VER
+#   define NORETURN __declspec(noreturn)
+#elif defined __GNUC__
+#   define NORETURN __attribute__ ((noreturn))
+#else
+#   define NORETURN
+#endif
+
+static char __testlib_format_buffer[16777216];
+static int __testlib_format_buffer_usage_count = 0;
+
+#define FMT_TO_RESULT(fmt, cstr, result)  std::string result;                              \
+            if (__testlib_format_buffer_usage_count != 0)                                  \
+                __testlib_fail("FMT_TO_RESULT::__testlib_format_buffer_usage_count != 0"); \
+            __testlib_format_buffer_usage_count++;                                         \
+            va_list ap;                                                                    \
+            va_start(ap, fmt);                                                             \
+            vsnprintf(__testlib_format_buffer, sizeof(__testlib_format_buffer), cstr, ap); \
+            va_end(ap);                                                                    \
+            __testlib_format_buffer[sizeof(__testlib_format_buffer) - 1] = 0;              \
+            result = std::string(__testlib_format_buffer);                                 \
+            __testlib_format_buffer_usage_count--;                                         \
+
+#ifdef __GNUC__
+__attribute__ ((format (printf, 1, 2)))
+#endif
+std::string testlib_format_(const char *fmt, ...);
+std::string testlib_format_(const std::string fmt, ...);
+
+const long long __TESTLIB_LONGLONG_MAX = 9223372036854775807LL;
+const int __TESTLIB_MAX_TEST_CASE = 1073741823;
+
+int __testlib_exitCode;
+
+bool __testlib_hasTestCase;
+int __testlib_testCase = -1;
+
+void setTestCase(int testCase);
+
+void unsetTestCase() {
+    __testlib_hasTestCase = false;
+    __testlib_testCase = -1;
+}
+
+NORETURN static void __testlib_fail(const std::string &message);
+
+template<typename T>
+#ifdef __GNUC__
+__attribute__((const))
+#endif
+static inline T __testlib_abs(const T &x) {
+    return x > 0 ? x : -x;
+}
+
+template<typename T>
+#ifdef __GNUC__
+__attribute__((const))
+#endif
+static inline T __testlib_min(const T &a, const T &b) {
+    return a < b ? a : b;
+}
+
+template<typename T>
+#ifdef __GNUC__
+__attribute__((const))
+#endif
+static inline T __testlib_max(const T &a, const T &b) {
+    return a > b ? a : b;
+}
+
+template<typename T>
+#ifdef __GNUC__
+__attribute__((const))
+#endif
+static inline T __testlib_crop(T value, T a, T b) {
+    return __testlib_min(__testlib_max(value, a), --b);
+}
+
+#ifdef __GNUC__
+__attribute__((const))
+#endif
+static inline double __testlib_crop(double value, double a, double b) {
+    value = __testlib_min(__testlib_max(value, a), b);
+    if (value >= b)
+        value = std::nexttoward(b, a);
+    return value;
+}
+
+static bool __testlib_prelimIsNaN(double r) {
+    volatile double ra = r;
+#ifndef __BORLANDC__
+    return ((ra != ra) == true) && ((ra == ra) == false) && ((1.0 > ra) == false) && ((1.0 < ra) == false);
+#else
+    return std::_isnan(ra);
+#endif
+}
+
+#ifdef __GNUC__
+__attribute__((const))
+#endif
+static std::string removeDoubleTrailingZeroes(std::string value) {
+    while (!value.empty() && value[value.length() - 1] == '0' && value.find('.') != std::string::npos)
+        value = value.substr(0, value.length() - 1);
+    if (!value.empty() && value[value.length() - 1] == '.')
+        return value + '0';
+    else
+        return value;
+}
+
+#ifdef __GNUC__
+__attribute__((const))
+#endif
+inline std::string upperCase(std::string s) {
+    for (size_t i = 0; i < s.length(); i++)
+        if ('a' <= s[i] && s[i] <= 'z')
+            s[i] = char(s[i] - 'a' + 'A');
+    return s;
+}
+
+#ifdef __GNUC__
+__attribute__((const))
+#endif
+inline std::string lowerCase(std::string s) {
+    for (size_t i = 0; i < s.length(); i++)
+        if ('A' <= s[i] && s[i] <= 'Z')
+            s[i] = char(s[i] - 'A' + 'a');
+    return s;
+}
+
+#ifdef __GNUC__
+__attribute__((const))
+#endif
+static std::string __testlib_part(const std::string &s);
+
+static bool __testlib_isNaN(double r) {
+    __TESTLIB_STATIC_ASSERT(sizeof(double) == sizeof(long long));
+    volatile double ra = r;
+    long long llr1, llr2;
+    std::memcpy((void *) &llr1, (void *) &ra, sizeof(double));
+    ra = -ra;
+    std::memcpy((void *) &llr2, (void *) &ra, sizeof(double));
+    long long llnan = 0xFFF8000000000000LL;
+    return __testlib_prelimIsNaN(r) || llnan == llr1 || llnan == llr2;
+}
+
+static double __testlib_nan() {
+    __TESTLIB_STATIC_ASSERT(sizeof(double) == sizeof(long long));
+#ifndef NAN
+    long long llnan = 0xFFF8000000000000LL;
+    double nan;
+    std::memcpy(&nan, &llnan, sizeof(double));
+    return nan;
+#else
+    return NAN;
+#endif
+}
+
+static bool __testlib_isInfinite(double r) {
+    volatile double ra = r;
+    return (ra > 1E300 || ra < -1E300);
+}
+
+#ifdef __GNUC__
+__attribute__((const))
+#endif
+inline bool doubleCompare(double expected, double result, double MAX_DOUBLE_ERROR) {
+    MAX_DOUBLE_ERROR += 1E-15;
+    if (__testlib_isNaN(expected)) {
+        return __testlib_isNaN(result);
+    } else if (__testlib_isInfinite(expected)) {
+        if (expected > 0) {
+            return result > 0 && __testlib_isInfinite(result);
+        } else {
+            return result < 0 && __testlib_isInfinite(result);
+        }
+    } else if (__testlib_isNaN(result) || __testlib_isInfinite(result)) {
+        return false;
+    } else if (__testlib_abs(result - expected) <= MAX_DOUBLE_ERROR) {
+        return true;
+    } else {
+        double minv = __testlib_min(expected * (1.0 - MAX_DOUBLE_ERROR),
+                                    expected * (1.0 + MAX_DOUBLE_ERROR));
+        double maxv = __testlib_max(expected * (1.0 - MAX_DOUBLE_ERROR),
+                                    expected * (1.0 + MAX_DOUBLE_ERROR));
+        return result >= minv && result <= maxv;
+    }
+}
+
+#ifdef __GNUC__
+__attribute__((const))
+#endif
+inline double doubleDelta(double expected, double result) {
+    double absolute = __testlib_abs(result - expected);
+
+    if (__testlib_abs(expected) > 1E-9) {
+        double relative = __testlib_abs(absolute / expected);
+        return __testlib_min(absolute, relative);
+    } else
+        return absolute;
+}
+
+/** It does nothing on non-windows and files differ from stdin/stdout/stderr. */
+static void __testlib_set_binary(std::FILE *file) {
+    if (NULL != file) {
+#ifdef ON_WINDOWS
+#   ifdef _O_BINARY
+        if (stdin == file)
+#       ifdef STDIN_FILENO
+                return void(_setmode(STDIN_FILENO, _O_BINARY));
+#       else
+                return void(_setmode(_fileno(stdin), _O_BINARY));
+#       endif
+        if (stdout == file)
+#       ifdef STDOUT_FILENO
+                return void(_setmode(STDOUT_FILENO, _O_BINARY));
+#       else
+                return void(_setmode(_fileno(stdout), _O_BINARY));
+#       endif
+        if (stderr == file)
+#       ifdef STDERR_FILENO
+                return void(_setmode(STDERR_FILENO, _O_BINARY));
+#       else
+                return void(_setmode(_fileno(stderr), _O_BINARY));
+#       endif
+#   elif O_BINARY
+        if (stdin == file)
+#       ifdef STDIN_FILENO
+                return void(setmode(STDIN_FILENO, O_BINARY));
+#       else
+                return void(setmode(fileno(stdin), O_BINARY));
+#       endif
+        if (stdout == file)
+#       ifdef STDOUT_FILENO
+                return void(setmode(STDOUT_FILENO, O_BINARY));
+#       else
+                return void(setmode(fileno(stdout), O_BINARY));
+#       endif
+        if (stderr == file)
+#       ifdef STDERR_FILENO
+                return void(setmode(STDERR_FILENO, O_BINARY));
+#       else
+                return void(setmode(fileno(stderr), O_BINARY));
+#       endif
+#   endif
+#endif
+    }
+}
+
+#if __cplusplus > 199711L || defined(_MSC_VER)
+template<typename T>
+#ifdef __GNUC__
+__attribute__((const))
+#endif
+static std::string vtos(const T &t, std::true_type) {
+    if (t == 0)
+        return "0";
+    else {
+        T n(t);
+        bool negative = n < 0;
+        std::string s;
+        while (n != 0) {
+            T digit = n % 10;
+            if (digit < 0)
+                digit = -digit;
+            s += char('0' + digit);
+            n /= 10;
+        }
+        std::reverse(s.begin(), s.end());
+        return negative ? "-" + s : s;
+    }
+}
+
+template<typename T>
+static std::string vtos(const T &t, std::false_type) {
+    std::string s;
+    static std::stringstream ss;
+    ss.str(std::string());
+    ss.clear();
+    ss << t;
+    ss >> s;
+    return s;
+}
+
+template<typename T>
+static std::string vtos(const T &t) {
+    return vtos(t, std::is_integral<T>());
+}
+
+/* signed case. */
+template<typename T>
+static std::string toHumanReadableString(const T &n, std::false_type) {
+    if (n == 0)
+        return vtos(n);
+    int trailingZeroCount = 0;
+    T n_ = n;
+    while (n_ % 10 == 0)
+        n_ /= 10, trailingZeroCount++;
+    if (trailingZeroCount >= 7) {
+        if (n_ == 1)
+            return "10^" + vtos(trailingZeroCount);
+        else if (n_ == -1)
+            return "-10^" + vtos(trailingZeroCount);
+        else
+            return vtos(n_) + "*10^" + vtos(trailingZeroCount);
+    } else
+        return vtos(n);
+}
+
+/* unsigned case. */
+template<typename T>
+static std::string toHumanReadableString(const T &n, std::true_type) {
+    if (n == 0)
+        return vtos(n);
+    int trailingZeroCount = 0;
+    T n_ = n;
+    while (n_ % 10 == 0)
+        n_ /= 10, trailingZeroCount++;
+    if (trailingZeroCount >= 7) {
+        if (n_ == 1)
+            return "10^" + vtos(trailingZeroCount);
+        else
+            return vtos(n_) + "*10^" + vtos(trailingZeroCount);
+    } else
+        return vtos(n);
+}
+
+template<typename T>
+static std::string toHumanReadableString(const T &n) {
+    return toHumanReadableString(n, std::is_unsigned<T>());
+}
+#else
+template<typename T>
+static std::string vtos(const T& t)
+{
+    std::string s;
+    static std::stringstream ss;
+    ss.str(std::string());
+    ss.clear();
+    ss << t;
+    ss >> s;
+    return s;
+}
+
+template<typename T>
+static std::string toHumanReadableString(const T &n) {
+    return vtos(n);
+}
+#endif
+
+template<typename T>
+static std::string toString(const T &t) {
+    return vtos(t);
+}
+
+#if __cplusplus > 199711L || defined(_MSC_VER)
+/* opts */
+void prepareOpts(int argc, char* argv[]);
+#endif
+
+FILE* testlib_fopen_(const char* path, const char* mode) {
+#ifdef _MSC_VER
+    FILE* result = NULL;
+    if (fopen_s(&result, path, mode) != 0)
+        return NULL;
+    else
+        return result;
+#else
+        return std::fopen(path, mode);
+#endif
+}
+
+FILE* testlib_freopen_(const char* path, const char* mode, FILE* file) {
+#ifdef _MSC_VER
+    FILE* result = NULL;
+    if (freopen_s(&result, path, mode, file) != 0)
+        return NULL;
+    else
+        return result;
+#else
+    return std::freopen(path, mode, file);
+#endif
+}
+
+/*
+ * Very simple regex-like pattern.
+ * It used for two purposes: validation and generation.
+ *
+ * For example, pattern("[a-z]{1,5}").next(rnd) will return
+ * random string from lowercase latin letters with length
+ * from 1 to 5. It is easier to call rnd.next("[a-z]{1,5}")
+ * for the same effect.
+ *
+ * Another samples:
+ * "mike|john" will generate (match) "mike" or "john";
+ * "-?[1-9][0-9]{0,3}" will generate (match) non-zero integers from -9999 to 9999;
+ * "id-([ac]|b{2})" will generate (match) "id-a", "id-bb", "id-c";
+ * "[^0-9]*" will match sequences (empty or non-empty) without digits, you can't
+ * use it for generations.
+ *
+ * You can't use pattern for generation if it contains meta-symbol '*'. Also it
+ * is not recommended to use it for char-sets with meta-symbol '^' like [^a-z].
+ *
+ * For matching very simple greedy algorithm is used. For example, pattern
+ * "[0-9]?1" will not match "1", because of greedy nature of matching.
+ * Alternations (meta-symbols "|") are processed with brute-force algorithm, so
+ * do not use many alternations in one expression.
+ *
+ * If you want to use one expression many times it is better to compile it into
+ * a single pattern like "pattern p("[a-z]+")". Later you can use
+ * "p.matches(std::string s)" or "p.next(random_t& rd)" to check matching or generate
+ * new string by pattern.
+ *
+ * Simpler way to read token and check it for pattern matching is "inf.readToken("[a-z]+")".
+ *
+ * All spaces are ignored in regex, unless escaped with \. For example, ouf.readLine("NO SOLUTION")
+ * will expect "NOSOLUTION", the correct call should be ouf.readLine("NO\\ SOLUTION") or
+ * ouf.readLine(R"(NO\ SOLUTION)") if you prefer raw string literals from C++11.
+ */
+class random_t;
+
+class pattern {
+public:
+    /* Create pattern instance by string. */
+    pattern(std::string s);
+
+    /* Generate new string by pattern and given random_t. */
+    std::string next(random_t &rnd) const;
+
+    /* Checks if given string match the pattern. */
+    bool matches(const std::string &s) const;
+
+    /* Returns source string of the pattern. */
+    std::string src() const;
+
+private:
+    bool matches(const std::string &s, size_t pos) const;
+
+    std::string s;
+    std::vector<pattern> children;
+    std::vector<char> chars;
+    int from;
+    int to;
+};
+
+/*
+ * Use random_t instances to generate random values. It is preferred
+ * way to use randoms instead of rand() function or self-written
+ * randoms.
+ *
+ * Testlib defines global variable "rnd" of random_t class.
+ * Use registerGen(argc, argv, 1) to setup random_t seed be command
+ * line (to use latest random generator version).
+ *
+ * Random generates uniformly distributed values if another strategy is
+ * not specified explicitly.
+ */
+class random_t {
+private:
+    unsigned long long seed;
+    static const unsigned long long multiplier;
+    static const unsigned long long addend;
+    static const unsigned long long mask;
+    static const int lim;
+
+    long long nextBits(int bits) {
+        if (bits <= 48) {
+            seed = (seed * multiplier + addend) & mask;
+            return (long long) (seed >> (48 - bits));
+        } else {
+            if (bits > 63)
+                __testlib_fail("random_t::nextBits(int bits): n must be less than 64");
+
+            int lowerBitCount = (random_t::version == 0 ? 31 : 32);
+
+            long long left = (nextBits(31) << 32);
+            long long right = nextBits(lowerBitCount);
+
+            return left ^ right;
+        }
+    }
+
+public:
+    static int version;
+
+    /* New random_t with fixed seed. */
+    random_t()
+            : seed(3905348978240129619LL) {
+    }
+
+    /* Sets seed by command line. */
+    void setSeed(int argc, char *argv[]) {
+        random_t p;
+
+        seed = 3905348978240129619LL;
+        for (int i = 1; i < argc; i++) {
+            std::size_t le = std::strlen(argv[i]);
+            for (std::size_t j = 0; j < le; j++)
+                seed = seed * multiplier + (unsigned int) (argv[i][j]) + addend;
+            seed += multiplier / addend;
+        }
+
+        seed = seed & mask;
+    }
+
+    /* Sets seed by given value. */
+    void setSeed(long long _seed) {
+        seed = (unsigned long long) _seed;
+        seed = (seed ^ multiplier) & mask;
+    }
+
+#ifndef __BORLANDC__
+
+    /* Random string value by given pattern (see pattern documentation). */
+    std::string next(const std::string &ptrn) {
+        pattern p(ptrn);
+        return p.next(*this);
+    }
+
+#else
+    /* Random string value by given pattern (see pattern documentation). */
+    std::string next(std::string ptrn)
+    {
+        pattern p(ptrn);
+        return p.next(*this);
+    }
+#endif
+
+    /* Random value in range [0, n-1]. */
+    int next(int n) {
+        if (n <= 0)
+            __testlib_fail("random_t::next(int n): n must be positive");
+
+        if ((n & -n) == n)  // n is a power of 2
+            return (int) ((n * (long long) nextBits(31)) >> 31);
+
+        const long long limit = INT_MAX / n * n;
+
+        long long bits;
+        do {
+            bits = nextBits(31);
+        } while (bits >= limit);
+
+        return int(bits % n);
+    }
+
+    /* Random value in range [0, n-1]. */
+    unsigned int next(unsigned int n) {
+        if (n >= INT_MAX)
+            __testlib_fail("random_t::next(unsigned int n): n must be less INT_MAX");
+        return (unsigned int) next(int(n));
+    }
+
+    /* Random value in range [0, n-1]. */
+    long long next(long long n) {
+        if (n <= 0)
+            __testlib_fail("random_t::next(long long n): n must be positive");
+
+        const long long limit = __TESTLIB_LONGLONG_MAX / n * n;
+
+        long long bits;
+        do {
+            bits = nextBits(63);
+        } while (bits >= limit);
+
+        return bits % n;
+    }
+
+    /* Random value in range [0, n-1]. */
+    unsigned long long next(unsigned long long n) {
+        if (n >= (unsigned long long) (__TESTLIB_LONGLONG_MAX))
+            __testlib_fail("random_t::next(unsigned long long n): n must be less LONGLONG_MAX");
+        return (unsigned long long) next((long long) (n));
+    }
+
+    /* Random value in range [0, n-1]. */
+    long next(long n) {
+        return (long) next((long long) (n));
+    }
+
+    /* Random value in range [0, n-1]. */
+    unsigned long next(unsigned long n) {
+        if (n >= (unsigned long) (LONG_MAX))
+            __testlib_fail("random_t::next(unsigned long n): n must be less LONG_MAX");
+        return (unsigned long) next((unsigned long long) (n));
+    }
+
+    /* Returns random value in range [from,to]. */
+    int next(int from, int to) {
+        return int(next((long long) to - from + 1) + from);
+    }
+
+    /* Returns random value in range [from,to]. */
+    unsigned int next(unsigned int from, unsigned int to) {
+        return (unsigned int) (next((long long) to - from + 1) + from);
+    }
+
+    /* Returns random value in range [from,to]. */
+    long long next(long long from, long long to) {
+        return next(to - from + 1) + from;
+    }
+
+    /* Returns random value in range [from,to]. */
+    unsigned long long next(unsigned long long from, unsigned long long to) {
+        if (from > to)
+            __testlib_fail("random_t::next(unsigned long long from, unsigned long long to): from can't not exceed to");
+        return next(to - from + 1) + from;
+    }
+
+    /* Returns random value in range [from,to]. */
+    long next(long from, long to) {
+        return next(to - from + 1) + from;
+    }
+
+    /* Returns random value in range [from,to]. */
+    unsigned long next(unsigned long from, unsigned long to) {
+        if (from > to)
+            __testlib_fail("random_t::next(unsigned long from, unsigned long to): from can't not exceed to");
+        return next(to - from + 1) + from;
+    }
+
+    /* Random double value in range [0, 1). */
+    double next() {
+        long long left = ((long long) (nextBits(26)) << 27);
+        long long right = nextBits(27);
+        return __testlib_crop((double) (left + right) / (double) (1LL << 53), 0.0, 1.0);
+    }
+
+    /* Random double value in range [0, n). */
+    double next(double n) {
+        if (n <= 0.0)
+            __testlib_fail("random_t::next(double): n should be positive");
+        return __testlib_crop(n * next(), 0.0, n);
+    }
+
+    /* Random double value in range [from, to). */
+    double next(double from, double to) {
+        if (from >= to)
+            __testlib_fail("random_t::next(double from, double to): from should be strictly less than to");
+        return next(to - from) + from;
+    }
+
+    /* Returns random element from container. */
+    template<typename Container>
+    typename Container::value_type any(const Container &c) {
+        int size = int(c.size());
+        if (size <= 0)
+            __testlib_fail("random_t::any(const Container& c): c.size() must be positive");
+        typename Container::const_iterator it = c.begin();
+        std::advance(it, next(size));
+        return *it;
+    }
+
+    /* Returns random element from iterator range. */
+    template<typename Iter>
+    typename Iter::value_type any(const Iter &begin, const Iter &end) {
+        int size = static_cast<int>(std::distance(begin, end));
+        if (size <= 0)
+            __testlib_fail("random_t::any(const Iter& begin, const Iter& end): range must have positive length");
+        Iter it = begin;
+        std::advance(it, next(size));
+        return *it;
+    }
+
+    /* Random string value by given pattern (see pattern documentation). */
+#ifdef __GNUC__
+    __attribute__ ((format (printf, 2, 3)))
+#endif
+    std::string next(const char *format, ...) {
+        FMT_TO_RESULT(format, format, ptrn);
+        return next(ptrn);
+    }
+
+    /*
+     * Weighted next. If type == 0 than it is usual "next()".
+     *
+     * If type = 1, than it returns "max(next(), next())"
+     * (the number of "max" functions equals to "type").
+     *
+     * If type < 0, than "max" function replaces with "min".
+     */
+    int wnext(int n, int type) {
+        if (n <= 0)
+            __testlib_fail("random_t::wnext(int n, int type): n must be positive");
+
+        if (abs(type) < random_t::lim) {
+            int result = next(n);
+
+            for (int i = 0; i < +type; i++)
+                result = __testlib_max(result, next(n));
+
+            for (int i = 0; i < -type; i++)
+                result = __testlib_min(result, next(n));
+
+            return result;
+        } else {
+            double p;
+
+            if (type > 0)
+                p = std::pow(next() + 0.0, 1.0 / (type + 1));
+            else
+                p = 1 - std::pow(next() + 0.0, 1.0 / (-type + 1));
+
+            return __testlib_crop((int) (double(n) * p), 0, n);
+        }
+    }
+
+    /* See wnext(int, int). It uses the same algorithms. */
+    long long wnext(long long n, int type) {
+        if (n <= 0)
+            __testlib_fail("random_t::wnext(long long n, int type): n must be positive");
+
+        if (abs(type) < random_t::lim) {
+            long long result = next(n);
+
+            for (int i = 0; i < +type; i++)
+                result = __testlib_max(result, next(n));
+
+            for (int i = 0; i < -type; i++)
+                result = __testlib_min(result, next(n));
+
+            return result;
+        } else {
+            double p;
+
+            if (type > 0)
+                p = std::pow(next() + 0.0, 1.0 / (type + 1));
+            else
+                p = 1 - std::pow(next() + 0.0, 1.0 / (-type + 1));
+
+            return __testlib_crop((long long) (double(n) * p), 0LL, n);
+        }
+    }
+
+    /* Returns value in [0, n). See wnext(int, int). It uses the same algorithms. */
+    double wnext(double n, int type) {
+        if (n <= 0)
+            __testlib_fail("random_t::wnext(double n, int type): n must be positive");
+
+        if (abs(type) < random_t::lim) {
+            double result = next();
+
+            for (int i = 0; i < +type; i++)
+                result = __testlib_max(result, next());
+
+            for (int i = 0; i < -type; i++)
+                result = __testlib_min(result, next());
+
+            return n * result;
+        } else {
+            double p;
+
+            if (type > 0)
+                p = std::pow(next() + 0.0, 1.0 / (type + 1));
+            else
+                p = 1 - std::pow(next() + 0.0, 1.0 / (-type + 1));
+
+            return __testlib_crop(n * p, 0.0, n);
+        }
+    }
+
+    /* Returns value in [0, 1). See wnext(int, int). It uses the same algorithms. */
+    double wnext(int type) {
+        return wnext(1.0, type);
+    }
+
+    /* See wnext(int, int). It uses the same algorithms. */
+    unsigned int wnext(unsigned int n, int type) {
+        if (n >= INT_MAX)
+            __testlib_fail("random_t::wnext(unsigned int n, int type): n must be less INT_MAX");
+        return (unsigned int) wnext(int(n), type);
+    }
+
+    /* See wnext(int, int). It uses the same algorithms. */
+    unsigned long long wnext(unsigned long long n, int type) {
+        if (n >= (unsigned long long) (__TESTLIB_LONGLONG_MAX))
+            __testlib_fail("random_t::wnext(unsigned long long n, int type): n must be less LONGLONG_MAX");
+
+        return (unsigned long long) wnext((long long) (n), type);
+    }
+
+    /* See wnext(int, int). It uses the same algorithms. */
+    long wnext(long n, int type) {
+        return (long) wnext((long long) (n), type);
+    }
+
+    /* See wnext(int, int). It uses the same algorithms. */
+    unsigned long wnext(unsigned long n, int type) {
+        if (n >= (unsigned long) (LONG_MAX))
+            __testlib_fail("random_t::wnext(unsigned long n, int type): n must be less LONG_MAX");
+
+        return (unsigned long) wnext((unsigned long long) (n), type);
+    }
+
+    /* Returns weighted random value in range [from, to]. */
+    int wnext(int from, int to, int type) {
+        if (from > to)
+            __testlib_fail("random_t::wnext(int from, int to, int type): from can't not exceed to");
+        return wnext(to - from + 1, type) + from;
+    }
+
+    /* Returns weighted random value in range [from, to]. */
+    int wnext(unsigned int from, unsigned int to, int type) {
+        if (from > to)
+            __testlib_fail("random_t::wnext(unsigned int from, unsigned int to, int type): from can't not exceed to");
+        return int(wnext(to - from + 1, type) + from);
+    }
+
+    /* Returns weighted random value in range [from, to]. */
+    long long wnext(long long from, long long to, int type) {
+        if (from > to)
+            __testlib_fail("random_t::wnext(long long from, long long to, int type): from can't not exceed to");
+        return wnext(to - from + 1, type) + from;
+    }
+
+    /* Returns weighted random value in range [from, to]. */
+    unsigned long long wnext(unsigned long long from, unsigned long long to, int type) {
+        if (from > to)
+            __testlib_fail(
+                    "random_t::wnext(unsigned long long from, unsigned long long to, int type): from can't not exceed to");
+        return wnext(to - from + 1, type) + from;
+    }
+
+    /* Returns weighted random value in range [from, to]. */
+    long wnext(long from, long to, int type) {
+        if (from > to)
+            __testlib_fail("random_t::wnext(long from, long to, int type): from can't not exceed to");
+        return wnext(to - from + 1, type) + from;
+    }
+
+    /* Returns weighted random value in range [from, to]. */
+    unsigned long wnext(unsigned long from, unsigned long to, int type) {
+        if (from > to)
+            __testlib_fail("random_t::wnext(unsigned long from, unsigned long to, int type): from can't not exceed to");
+        return wnext(to - from + 1, type) + from;
+    }
+
+    /* Returns weighted random double value in range [from, to). */
+    double wnext(double from, double to, int type) {
+        if (from >= to)
+            __testlib_fail("random_t::wnext(double from, double to, int type): from should be strictly less than to");
+        return wnext(to - from, type) + from;
+    }
+
+    /* Returns weighted random element from container. */
+    template<typename Container>
+    typename Container::value_type wany(const Container &c, int type) {
+        int size = int(c.size());
+        if (size <= 0)
+            __testlib_fail("random_t::wany(const Container& c, int type): c.size() must be positive");
+        typename Container::const_iterator it = c.begin();
+        std::advance(it, wnext(size, type));
+        return *it;
+    }
+
+    /* Returns weighted random element from iterator range. */
+    template<typename Iter>
+    typename Iter::value_type wany(const Iter &begin, const Iter &end, int type) {
+        int size = static_cast<int>(std::distance(begin, end));
+        if (size <= 0)
+            __testlib_fail(
+                    "random_t::any(const Iter& begin, const Iter& end, int type): range must have positive length");
+        Iter it = begin;
+        std::advance(it, wnext(size, type));
+        return *it;
+    }
+
+    /* Returns random permutation of the given size (values are between `first` and `first`+size-1)*/
+    template<typename T, typename E>
+    std::vector<E> perm(T size, E first) {
+        if (size < 0)
+            __testlib_fail("random_t::perm(T size, E first = 0): size must non-negative");
+        else if (size == 0)
+            return std::vector<E>();
+        std::vector<E> p(size);
+        E current = first;
+        for (T i = 0; i < size; i++)
+            p[i] = current++;
+        if (size > 1)
+            for (T i = 1; i < size; i++)
+                std::swap(p[i], p[next(i + 1)]);
+        return p;
+    }
+
+    /* Returns random permutation of the given size (values are between 0 and size-1)*/
+    template<typename T>
+    std::vector<T> perm(T size) {
+        return perm(size, T(0));
+    }
+
+    /* Returns `size` unordered (unsorted) distinct numbers between `from` and `to`. */
+    template<typename T>
+    std::vector<T> distinct(int size, T from, T to) {
+        std::vector<T> result;
+        if (size == 0)
+            return result;
+
+        if (from > to)
+            __testlib_fail("random_t::distinct expected from <= to");
+
+        if (size < 0)
+            __testlib_fail("random_t::distinct expected size >= 0");
+
+        uint64_t n = to - from + 1;
+        if (uint64_t(size) > n)
+            __testlib_fail("random_t::distinct expected size <= to - from + 1");
+
+        double expected = 0.0;
+        for (int i = 1; i <= size; i++)
+            expected += double(n) / double(n - i + 1);
+
+        if (expected < double(n)) {
+            std::set<T> vals;
+            while (int(vals.size()) < size) {
+                T x = T(next(from, to));
+                if (vals.insert(x).second)
+                    result.push_back(x);
+            }
+        } else {
+            if (n > 1000000000)
+                __testlib_fail("random_t::distinct here expected to - from + 1 <= 1000000000");
+            std::vector<T> p(perm(int(n), from));
+            result.insert(result.end(), p.begin(), p.begin() + size);
+        }
+
+        return result;
+    }
+
+    /* Returns `size` unordered (unsorted) distinct numbers between `0` and `upper`-1. */
+    template<typename T>
+    std::vector<T> distinct(int size, T upper) {
+        if (size < 0)
+            __testlib_fail("random_t::distinct expected size >= 0");
+        if (size == 0)
+            return std::vector<T>();
+
+        if (upper <= 0)
+            __testlib_fail("random_t::distinct expected upper > 0");
+        if (size > upper)
+            __testlib_fail("random_t::distinct expected size <= upper");
+
+        return distinct(size, T(0), upper - 1);
+    }
+
+    /* Returns random (unsorted) partition which is a representation of sum as a sum of integers not less than min_part. */
+    template<typename T>
+    std::vector<T> partition(int size, T sum, T min_part) {
+        if (size < 0)
+            __testlib_fail("random_t::partition: size < 0");
+        if (size == 0 && sum != 0)
+            __testlib_fail("random_t::partition: size == 0 && sum != 0");
+        if (min_part * size > sum)
+            __testlib_fail("random_t::partition: min_part * size > sum");
+        if (size == 0 && sum == 0)
+            return std::vector<T>();
+
+        T sum_ = sum;
+        sum -= min_part * size;
+
+        std::vector<T> septums(size);
+        std::vector<T> d = distinct(size - 1, T(1), T(sum + size - 1));
+        for (int i = 0; i + 1 < size; i++)
+            septums[i + 1] = d[i];
+        sort(septums.begin(), septums.end());
+
+        std::vector<T> result(size);
+        for (int i = 0; i + 1 < size; i++)
+            result[i] = septums[i + 1] - septums[i] - 1;
+        result[size - 1] = sum + size - 1 - septums.back();
+
+        for (std::size_t i = 0; i < result.size(); i++)
+            result[i] += min_part;
+
+        T result_sum = 0;
+        for (std::size_t i = 0; i < result.size(); i++)
+            result_sum += result[i];
+        if (result_sum != sum_)
+            __testlib_fail("random_t::partition: partition sum is expected to be the given sum");
+
+        if (*std::min_element(result.begin(), result.end()) < min_part)
+            __testlib_fail("random_t::partition: partition min is expected to be no less than the given min_part");
+
+        if (int(result.size()) != size || result.size() != (size_t) size)
+            __testlib_fail("random_t::partition: partition size is expected to be equal to the given size");
+
+        return result;
+    }
+
+    /* Returns random (unsorted) partition which is a representation of sum as a sum of positive integers. */
+    template<typename T>
+    std::vector<T> partition(int size, T sum) {
+        return partition(size, sum, T(1));
+    }
+};
+
+const int random_t::lim = 25;
+const unsigned long long random_t::multiplier = 0x5DEECE66DLL;
+const unsigned long long random_t::addend = 0xBLL;
+const unsigned long long random_t::mask = (1LL << 48) - 1;
+int random_t::version = -1;
+
+/* Pattern implementation */
+bool pattern::matches(const std::string &s) const {
+    return matches(s, 0);
+}
+
+static bool __pattern_isSlash(const std::string &s, size_t pos) {
+    return s[pos] == '\\';
+}
+
+#ifdef __GNUC__
+__attribute__((pure))
+#endif
+static bool __pattern_isCommandChar(const std::string &s, size_t pos, char value) {
+    if (pos >= s.length())
+        return false;
+
+    int slashes = 0;
+
+    int before = int(pos) - 1;
+    while (before >= 0 && s[before] == '\\')
+        before--, slashes++;
+
+    return slashes % 2 == 0 && s[pos] == value;
+}
+
+static char __pattern_getChar(const std::string &s, size_t &pos) {
+    if (__pattern_isSlash(s, pos))
+        pos += 2;
+    else
+        pos++;
+
+    return s[pos - 1];
+}
+
+#ifdef __GNUC__
+__attribute__((pure))
+#endif
+static int __pattern_greedyMatch(const std::string &s, size_t pos, const std::vector<char> chars) {
+    int result = 0;
+
+    while (pos < s.length()) {
+        char c = s[pos++];
+        if (!std::binary_search(chars.begin(), chars.end(), c))
+            break;
+        else
+            result++;
+    }
+
+    return result;
+}
+
+std::string pattern::src() const {
+    return s;
+}
+
+bool pattern::matches(const std::string &s, size_t pos) const {
+    std::string result;
+
+    if (to > 0) {
+        int size = __pattern_greedyMatch(s, pos, chars);
+        if (size < from)
+            return false;
+        if (size > to)
+            size = to;
+        pos += size;
+    }
+
+    if (children.size() > 0) {
+        for (size_t child = 0; child < children.size(); child++)
+            if (children[child].matches(s, pos))
+                return true;
+        return false;
+    } else
+        return pos == s.length();
+}
+
+std::string pattern::next(random_t &rnd) const {
+    std::string result;
+    result.reserve(20);
+
+    if (to == INT_MAX)
+        __testlib_fail("pattern::next(random_t& rnd): can't process character '*' for generation");
+
+    if (to > 0) {
+        int count = rnd.next(to - from + 1) + from;
+        for (int i = 0; i < count; i++)
+            result += chars[rnd.next(int(chars.size()))];
+    }
+
+    if (children.size() > 0) {
+        int child = rnd.next(int(children.size()));
+        result += children[child].next(rnd);
+    }
+
+    return result;
+}
+
+static void __pattern_scanCounts(const std::string &s, size_t &pos, int &from, int &to) {
+    if (pos >= s.length()) {
+        from = to = 1;
+        return;
+    }
+
+    if (__pattern_isCommandChar(s, pos, '{')) {
+        std::vector<std::string> parts;
+        std::string part;
+
+        pos++;
+
+        while (pos < s.length() && !__pattern_isCommandChar(s, pos, '}')) {
+            if (__pattern_isCommandChar(s, pos, ','))
+                parts.push_back(part), part = "", pos++;
+            else
+                part += __pattern_getChar(s, pos);
+        }
+
+        if (part != "")
+            parts.push_back(part);
+
+        if (!__pattern_isCommandChar(s, pos, '}'))
+            __testlib_fail("pattern: Illegal pattern (or part) \"" + s + "\"");
+
+        pos++;
+
+        if (parts.size() < 1 || parts.size() > 2)
+            __testlib_fail("pattern: Illegal pattern (or part) \"" + s + "\"");
+
+        std::vector<int> numbers;
+
+        for (size_t i = 0; i < parts.size(); i++) {
+            if (parts[i].length() == 0)
+                __testlib_fail("pattern: Illegal pattern (or part) \"" + s + "\"");
+            int number;
+#ifdef _MSC_VER
+            if (sscanf_s(parts[i].c_str(), "%d", &number) != 1)
+#else
+            if (std::sscanf(parts[i].c_str(), "%d", &number) != 1)
+#endif
+                __testlib_fail("pattern: Illegal pattern (or part) \"" + s + "\"");
+            numbers.push_back(number);
+        }
+
+        if (numbers.size() == 1)
+            from = to = numbers[0];
+        else
+            from = numbers[0], to = numbers[1];
+
+        if (from > to)
+            __testlib_fail("pattern: Illegal pattern (or part) \"" + s + "\"");
+    } else {
+        if (__pattern_isCommandChar(s, pos, '?')) {
+            from = 0, to = 1, pos++;
+            return;
+        }
+
+        if (__pattern_isCommandChar(s, pos, '*')) {
+            from = 0, to = INT_MAX, pos++;
+            return;
+        }
+
+        if (__pattern_isCommandChar(s, pos, '+')) {
+            from = 1, to = INT_MAX, pos++;
+            return;
+        }
+
+        from = to = 1;
+    }
+}
+
+static std::vector<char> __pattern_scanCharSet(const std::string &s, size_t &pos) {
+    if (pos >= s.length())
+        __testlib_fail("pattern: Illegal pattern (or part) \"" + s + "\"");
+
+    std::vector<char> result;
+
+    if (__pattern_isCommandChar(s, pos, '[')) {
+        pos++;
+        bool negative = __pattern_isCommandChar(s, pos, '^');
+        if (negative)
+            pos++;
+
+        char prev = 0;
+
+        while (pos < s.length() && !__pattern_isCommandChar(s, pos, ']')) {
+            if (__pattern_isCommandChar(s, pos, '-') && prev != 0) {
+                pos++;
+
+                if (pos + 1 == s.length() || __pattern_isCommandChar(s, pos, ']')) {
+                    result.push_back(prev);
+                    prev = '-';
+                    continue;
+                }
+
+                char next = __pattern_getChar(s, pos);
+                if (prev > next)
+                    __testlib_fail("pattern: Illegal pattern (or part) \"" + s + "\"");
+
+                for (char c = prev; c != next; c++)
+                    result.push_back(c);
+                result.push_back(next);
+
+                prev = 0;
+            } else {
+                if (prev != 0)
+                    result.push_back(prev);
+                prev = __pattern_getChar(s, pos);
+            }
+        }
+
+        if (prev != 0)
+            result.push_back(prev);
+
+        if (!__pattern_isCommandChar(s, pos, ']'))
+            __testlib_fail("pattern: Illegal pattern (or part) \"" + s + "\"");
+
+        pos++;
+
+        if (negative) {
+            std::sort(result.begin(), result.end());
+            std::vector<char> actuals;
+            for (int code = 0; code < 255; code++) {
+                char c = char(code);
+                if (!std::binary_search(result.begin(), result.end(), c))
+                    actuals.push_back(c);
+            }
+            result = actuals;
+        }
+
+        std::sort(result.begin(), result.end());
+    } else
+        result.push_back(__pattern_getChar(s, pos));
+
+    return result;
+}
+
+pattern::pattern(std::string s) : s(s), from(0), to(0) {
+    std::string t;
+    for (size_t i = 0; i < s.length(); i++)
+        if (!__pattern_isCommandChar(s, i, ' '))
+            t += s[i];
+    s = t;
+
+    int opened = 0;
+    int firstClose = -1;
+    std::vector<int> seps;
+
+    for (size_t i = 0; i < s.length(); i++) {
+        if (__pattern_isCommandChar(s, i, '(')) {
+            opened++;
+            continue;
+        }
+
+        if (__pattern_isCommandChar(s, i, ')')) {
+            opened--;
+            if (opened == 0 && firstClose == -1)
+                firstClose = int(i);
+            continue;
+        }
+
+        if (opened < 0)
+            __testlib_fail("pattern: Illegal pattern (or part) \"" + s + "\"");
+
+        if (__pattern_isCommandChar(s, i, '|') && opened == 0)
+            seps.push_back(int(i));
+    }
+
+    if (opened != 0)
+        __testlib_fail("pattern: Illegal pattern (or part) \"" + s + "\"");
+
+    if (seps.size() == 0 && firstClose + 1 == (int) s.length()
+        && __pattern_isCommandChar(s, 0, '(') && __pattern_isCommandChar(s, s.length() - 1, ')')) {
+        children.push_back(pattern(s.substr(1, s.length() - 2)));
+    } else {
+        if (seps.size() > 0) {
+            seps.push_back(int(s.length()));
+            int last = 0;
+
+            for (size_t i = 0; i < seps.size(); i++) {
+                children.push_back(pattern(s.substr(last, seps[i] - last)));
+                last = seps[i] + 1;
+            }
+        } else {
+            size_t pos = 0;
+            chars = __pattern_scanCharSet(s, pos);
+            __pattern_scanCounts(s, pos, from, to);
+            if (pos < s.length())
+                children.push_back(pattern(s.substr(pos)));
+        }
+    }
+}
+
+/* End of pattern implementation */
+
+template<typename C>
+inline bool isEof(C c) {
+    return c == EOFC;
+}
+
+template<typename C>
+inline bool isEoln(C c) {
+    return (c == LF || c == CR);
+}
+
+template<typename C>
+inline bool isBlanks(C c) {
+    return (c == LF || c == CR || c == SPACE || c == TAB);
+}
+
+inline std::string trim(const std::string &s) {
+    if (s.empty())
+        return s;
+
+    int left = 0;
+    while (left < int(s.length()) && isBlanks(s[left]))
+        left++;
+    if (left >= int(s.length()))
+        return "";
+
+    int right = int(s.length()) - 1;
+    while (right >= 0 && isBlanks(s[right]))
+        right--;
+    if (right < 0)
+        return "";
+
+    return s.substr(left, right - left + 1);
+}
+
+enum TMode {
+    _input, _output, _answer
+};
+
+/* Outcomes 6-15 are reserved for future use. */
+enum TResult {
+    _ok = 0,
+    _wa = 1,
+    _pe = 2,
+    _fail = 3,
+    _dirt = 4,
+    _points = 5,
+    _unexpected_eof = 8,
+    _partially = 16
+};
+
+enum TTestlibMode {
+    _unknown, _checker, _validator, _generator, _interactor, _scorer
+};
+
+#define _pc(exitCode) (TResult(_partially + (exitCode)))
+
+/* Outcomes 6-15 are reserved for future use. */
+const std::string outcomes[] = {
+        "accepted",
+        "wrong-answer",
+        "presentation-error",
+        "fail",
+        "fail",
+#ifndef PCMS2
+        "points",
+#else
+        "relative-scoring",
+#endif
+        "reserved",
+        "reserved",
+        "unexpected-eof",
+        "reserved",
+        "reserved",
+        "reserved",
+        "reserved",
+        "reserved",
+        "reserved",
+        "reserved",
+        "partially-correct"
+};
+
+class InputStreamReader {
+public:
+    virtual void setTestCase(int testCase) = 0;
+
+    virtual std::vector<int> getReadChars() = 0;
+    
+    virtual int curChar() = 0;
+
+    virtual int nextChar() = 0;
+
+    virtual void skipChar() = 0;
+
+    virtual void unreadChar(int c) = 0;
+
+    virtual std::string getName() = 0;
+
+    virtual bool eof() = 0;
+
+    virtual void close() = 0;
+
+    virtual int getLine() = 0;
+
+    virtual ~InputStreamReader() = 0;
+};
+
+InputStreamReader::~InputStreamReader() {
+    // No operations.
+}
+
+class StringInputStreamReader : public InputStreamReader {
+private:
+    std::string s;
+    size_t pos;
+
+public:
+    StringInputStreamReader(const std::string &content) : s(content), pos(0) {
+        // No operations.
+    }
+
+    void setTestCase(int) {
+        __testlib_fail("setTestCase not implemented in StringInputStreamReader");
+    }
+
+    std::vector<int> getReadChars() {
+        __testlib_fail("getReadChars not implemented in StringInputStreamReader");
+    }
+    
+    int curChar() {
+        if (pos >= s.length())
+            return EOFC;
+        else
+            return s[pos];
+    }
+
+    int nextChar() {
+        if (pos >= s.length()) {
+            pos++;
+            return EOFC;
+        } else
+            return s[pos++];
+    }
+
+    void skipChar() {
+        pos++;
+    }
+
+    void unreadChar(int c) {
+        if (pos == 0)
+            __testlib_fail("StringInputStreamReader::unreadChar(int): pos == 0.");
+        pos--;
+        if (pos < s.length())
+            s[pos] = char(c);
+    }
+
+    std::string getName() {
+        return __testlib_part(s);
+    }
+
+    int getLine() {
+        return -1;
+    }
+
+    bool eof() {
+        return pos >= s.length();
+    }
+
+    void close() {
+        // No operations.
+    }
+};
+
+class FileInputStreamReader : public InputStreamReader {
+private:
+    std::FILE *file;
+    std::string name;
+    int line;
+    std::vector<int> undoChars;
+    std::vector<int> readChars;
+    std::vector<int> undoReadChars;
+
+    inline int postprocessGetc(int getcResult) {
+        if (getcResult != EOF)
+            return getcResult;
+        else
+            return EOFC;
+    }
+
+    int getc(FILE *file) {
+        int c;
+        int rc;
+
+        if (undoChars.empty()) {
+            c = rc = ::getc(file);
+        } else {
+            c = undoChars.back();
+            undoChars.pop_back();
+            rc = undoReadChars.back();
+            undoReadChars.pop_back();
+        }
+
+        if (c == LF)
+            line++;
+
+        readChars.push_back(rc);
+        return c;
+    }
+
+    int ungetc(int c/*, FILE* file*/) {
+        if (!readChars.empty()) {
+            undoReadChars.push_back(readChars.back());
+            readChars.pop_back();
+        }
+        if (c == LF)
+            line--;
+        undoChars.push_back(c);
+        return c;
+    }
+
+public:
+    FileInputStreamReader(std::FILE *file, const std::string &name) : file(file), name(name), line(1) {
+        // No operations.
+    }
+
+    void setTestCase(int testCase) {
+        if (testCase < 0 || testCase > __TESTLIB_MAX_TEST_CASE)
+            __testlib_fail(testlib_format_("testCase expected fit in [1,%d], but %d doesn't", __TESTLIB_MAX_TEST_CASE, testCase));
+        readChars.push_back(testCase + 256);
+    }
+
+    std::vector<int> getReadChars() {
+        return readChars;
+    }
+
+    int curChar() {
+        if (feof(file))
+            return EOFC;
+        else {
+            int c = getc(file);
+            ungetc(c/*, file*/);
+            return postprocessGetc(c);
+        }
+    }
+
+    int nextChar() {
+        if (feof(file))
+            return EOFC;
+        else
+            return postprocessGetc(getc(file));
+    }
+
+    void skipChar() {
+        getc(file);
+    }
+
+    void unreadChar(int c) {
+        ungetc(c/*, file*/);
+    }
+
+    std::string getName() {
+        return name;
+    }
+
+    int getLine() {
+        return line;
+    }
+
+    bool eof() {
+        if (NULL == file || feof(file))
+            return true;
+        else {
+            int c = nextChar();
+            if (c == EOFC || (c == EOF && feof(file)))
+                return true;
+            unreadChar(c);
+            return false;
+        }
+    }
+
+    void close() {
+        if (NULL != file) {
+            fclose(file);
+            file = NULL;
+        }
+    }
+};
+
+class BufferedFileInputStreamReader : public InputStreamReader {
+private:
+    static const size_t BUFFER_SIZE;
+    static const size_t MAX_UNREAD_COUNT;
+
+    std::FILE *file;
+    std::string name;
+    int line;
+
+    char *buffer;
+    bool *isEof;
+    int bufferPos;
+    size_t bufferSize;
+
+    bool refill() {
+        if (NULL == file)
+            __testlib_fail("BufferedFileInputStreamReader: file == NULL (" + getName() + ")");
+
+        if (bufferPos >= int(bufferSize)) {
+            size_t readSize = fread(
+                    buffer + MAX_UNREAD_COUNT,
+                    1,
+                    BUFFER_SIZE - MAX_UNREAD_COUNT,
+                    file
+            );
+
+            if (readSize < BUFFER_SIZE - MAX_UNREAD_COUNT
+                && ferror(file))
+                __testlib_fail("BufferedFileInputStreamReader: unable to read (" + getName() + ")");
+
+            bufferSize = MAX_UNREAD_COUNT + readSize;
+            bufferPos = int(MAX_UNREAD_COUNT);
+            std::memset(isEof + MAX_UNREAD_COUNT, 0, sizeof(isEof[0]) * readSize);
+
+            return readSize > 0;
+        } else
+            return true;
+    }
+
+    char increment() {
+        char c;
+        if ((c = buffer[bufferPos++]) == LF)
+            line++;
+        return c;
+    }
+
+public:
+    BufferedFileInputStreamReader(std::FILE *file, const std::string &name) : file(file), name(name), line(1) {
+        buffer = new char[BUFFER_SIZE];
+        isEof = new bool[BUFFER_SIZE];
+        bufferSize = MAX_UNREAD_COUNT;
+        bufferPos = int(MAX_UNREAD_COUNT);
+    }
+
+    ~BufferedFileInputStreamReader() {
+        if (NULL != buffer) {
+            delete[] buffer;
+            buffer = NULL;
+        }
+        if (NULL != isEof) {
+            delete[] isEof;
+            isEof = NULL;
+        }
+    }
+
+    void setTestCase(int) {
+        __testlib_fail("setTestCase not implemented in BufferedFileInputStreamReader");
+    }
+
+    std::vector<int> getReadChars() {
+        __testlib_fail("getReadChars not implemented in BufferedFileInputStreamReader");
+    }
+    
+    int curChar() {
+        if (!refill())
+            return EOFC;
+
+        return isEof[bufferPos] ? EOFC : buffer[bufferPos];
+    }
+
+    int nextChar() {
+        if (!refill())
+            return EOFC;
+
+        return isEof[bufferPos] ? EOFC : increment();
+    }
+
+    void skipChar() {
+        increment();
+    }
+
+    void unreadChar(int c) {
+        bufferPos--;
+        if (bufferPos < 0)
+            __testlib_fail("BufferedFileInputStreamReader::unreadChar(int): bufferPos < 0");
+        isEof[bufferPos] = (c == EOFC);
+        buffer[bufferPos] = char(c);
+        if (c == LF)
+            line--;
+    }
+
+    std::string getName() {
+        return name;
+    }
+
+    int getLine() {
+        return line;
+    }
+
+    bool eof() {
+        return !refill() || EOFC == curChar();
+    }
+
+    void close() {
+        if (NULL != file) {
+            fclose(file);
+            file = NULL;
+        }
+    }
+};
+
+const size_t BufferedFileInputStreamReader::BUFFER_SIZE = 2000000;
+const size_t BufferedFileInputStreamReader::MAX_UNREAD_COUNT = BufferedFileInputStreamReader::BUFFER_SIZE / 2;
+
+/*
+ * Streams to be used for reading data in checkers or validators.
+ * Each read*() method moves pointer to the next character after the
+ * read value.
+ */
+struct InStream {
+    /* Do not use them. */
+    InStream();
+
+    ~InStream();
+
+    /* Wrap std::string with InStream. */
+    InStream(const InStream &baseStream, std::string content);
+
+    InputStreamReader *reader;
+    int lastLine;
+
+    std::string name;
+    TMode mode;
+    bool opened;
+    bool stdfile;
+    bool strict;
+
+    int wordReserveSize;
+    std::string _tmpReadToken;
+
+    int readManyIteration;
+    size_t maxFileSize;
+    size_t maxTokenLength;
+    size_t maxMessageLength;
+
+    void init(std::string fileName, TMode mode);
+
+    void init(std::FILE *f, TMode mode);
+
+    void setTestCase(int testCase);
+    std::vector<int> getReadChars();
+
+    /* Moves stream pointer to the first non-white-space character or EOF. */
+    void skipBlanks();
+
+    /* Returns current character in the stream. Doesn't remove it from stream. */
+    char curChar();
+
+    /* Moves stream pointer one character forward. */
+    void skipChar();
+
+    /* Returns current character and moves pointer one character forward. */
+    char nextChar();
+
+    /* Returns current character and moves pointer one character forward. */
+    char readChar();
+
+    /* As "readChar()" but ensures that the result is equal to given parameter. */
+    char readChar(char c);
+
+    /* As "readChar()" but ensures that the result is equal to the space (code=32). */
+    char readSpace();
+
+    /* Puts back the character into the stream. */
+    void unreadChar(char c);
+
+    /* Reopens stream, you should not use it. */
+    void reset(std::FILE *file = NULL);
+
+    /* Checks that current position is EOF. If not it doesn't move stream pointer. */
+    bool eof();
+
+    /* Moves pointer to the first non-white-space character and calls "eof()". */
+    bool seekEof();
+
+    /*
+     * Checks that current position contains EOLN.
+     * If not it doesn't move stream pointer.
+     * In strict mode expects "#13#10" for windows or "#10" for other platforms.
+     */
+    bool eoln();
+
+    /* Moves pointer to the first non-space and non-tab character and calls "eoln()". */
+    bool seekEoln();
+
+    /* Moves stream pointer to the first character of the next line (if exists). */
+    void nextLine();
+
+    /*
+     * Reads new token. Ignores white-spaces into the non-strict mode
+     * (strict mode is used in validators usually).
+     */
+    std::string readWord();
+
+    /* The same as "readWord()", it is preferred to use "readToken()". */
+    std::string readToken();
+
+    /* The same as "readWord()", but ensures that token matches to given pattern. */
+    std::string readWord(const std::string &ptrn, const std::string &variableName = "");
+
+    std::string readWord(const pattern &p, const std::string &variableName = "");
+
+    std::vector<std::string>
+    readWords(int size, const std::string &ptrn, const std::string &variablesName = "", int indexBase = 1);
+
+    std::vector<std::string>
+    readWords(int size, const pattern &p, const std::string &variablesName = "", int indexBase = 1);
+
+    std::vector<std::string> readWords(int size, int indexBase = 1);
+
+    /* The same as "readToken()", but ensures that token matches to given pattern. */
+    std::string readToken(const std::string &ptrn, const std::string &variableName = "");
+
+    std::string readToken(const pattern &p, const std::string &variableName = "");
+
+    std::vector<std::string>
+    readTokens(int size, const std::string &ptrn, const std::string &variablesName = "", int indexBase = 1);
+
+    std::vector<std::string>
+    readTokens(int size, const pattern &p, const std::string &variablesName = "", int indexBase = 1);
+
+    std::vector<std::string> readTokens(int size, int indexBase = 1);
+
+    void readWordTo(std::string &result);
+
+    void readWordTo(std::string &result, const pattern &p, const std::string &variableName = "");
+
+    void readWordTo(std::string &result, const std::string &ptrn, const std::string &variableName = "");
+
+    void readTokenTo(std::string &result);
+
+    void readTokenTo(std::string &result, const pattern &p, const std::string &variableName = "");
+
+    void readTokenTo(std::string &result, const std::string &ptrn, const std::string &variableName = "");
+
+    /*
+     * Reads new long long value. Ignores white-spaces into the non-strict mode
+     * (strict mode is used in validators usually).
+     */
+    long long readLong();
+
+    unsigned long long readUnsignedLong();
+
+    /*
+     * Reads new int. Ignores white-spaces into the non-strict mode
+     * (strict mode is used in validators usually).
+     */
+    int readInteger();
+
+    /*
+     * Reads new int. Ignores white-spaces into the non-strict mode
+     * (strict mode is used in validators usually).
+     */
+    int readInt();
+
+    /* As "readLong()" but ensures that value in the range [minv,maxv]. */
+    long long readLong(long long minv, long long maxv, const std::string &variableName = "");
+
+    /* Reads space-separated sequence of long longs. */
+    std::vector<long long>
+    readLongs(int size, long long minv, long long maxv, const std::string &variablesName = "", int indexBase = 1);
+
+    /* Reads space-separated sequence of long longs. */
+    std::vector<long long> readLongs(int size, int indexBase = 1);
+
+    unsigned long long
+    readUnsignedLong(unsigned long long minv, unsigned long long maxv, const std::string &variableName = "");
+
+    std::vector<unsigned long long>
+    readUnsignedLongs(int size, unsigned long long minv, unsigned long long maxv, const std::string &variablesName = "",
+                      int indexBase = 1);
+
+    std::vector<unsigned long long> readUnsignedLongs(int size, int indexBase = 1);
+
+    unsigned long long readLong(unsigned long long minv, unsigned long long maxv, const std::string &variableName = "");
+
+    std::vector<unsigned long long>
+    readLongs(int size, unsigned long long minv, unsigned long long maxv, const std::string &variablesName = "",
+              int indexBase = 1);
+
+    /* As "readInteger()" but ensures that value in the range [minv,maxv]. */
+    int readInteger(int minv, int maxv, const std::string &variableName = "");
+
+    /* As "readInt()" but ensures that value in the range [minv,maxv]. */
+    int readInt(int minv, int maxv, const std::string &variableName = "");
+
+    /* Reads space-separated sequence of integers. */
+    std::vector<int>
+    readIntegers(int size, int minv, int maxv, const std::string &variablesName = "", int indexBase = 1);
+
+    /* Reads space-separated sequence of integers. */
+    std::vector<int> readIntegers(int size, int indexBase = 1);
+
+    /* Reads space-separated sequence of integers. */
+    std::vector<int> readInts(int size, int minv, int maxv, const std::string &variablesName = "", int indexBase = 1);
+
+    /* Reads space-separated sequence of integers. */
+    std::vector<int> readInts(int size, int indexBase = 1);
+
+    /*
+     * Reads new double. Ignores white-spaces into the non-strict mode
+     * (strict mode is used in validators usually).
+     */
+    double readReal();
+
+    /*
+     * Reads new double. Ignores white-spaces into the non-strict mode
+     * (strict mode is used in validators usually).
+     */
+    double readDouble();
+
+    /* As "readReal()" but ensures that value in the range [minv,maxv]. */
+    double readReal(double minv, double maxv, const std::string &variableName = "");
+
+    std::vector<double>
+    readReals(int size, double minv, double maxv, const std::string &variablesName = "", int indexBase = 1);
+
+    std::vector<double> readReals(int size, int indexBase = 1);
+
+    /* As "readDouble()" but ensures that value in the range [minv,maxv]. */
+    double readDouble(double minv, double maxv, const std::string &variableName = "");
+
+    std::vector<double>
+    readDoubles(int size, double minv, double maxv, const std::string &variablesName = "", int indexBase = 1);
+
+    std::vector<double> readDoubles(int size, int indexBase = 1);
+
+    /*
+     * As "readReal()" but ensures that value in the range [minv,maxv] and
+     * number of digit after the decimal point is in range [minAfterPointDigitCount,maxAfterPointDigitCount]
+     * and number is in the form "[-]digit(s)[.digit(s)]".
+     */
+    double readStrictReal(double minv, double maxv,
+                          int minAfterPointDigitCount, int maxAfterPointDigitCount,
+                          const std::string &variableName = "");
+
+    std::vector<double> readStrictReals(int size, double minv, double maxv,
+                                        int minAfterPointDigitCount, int maxAfterPointDigitCount,
+                                        const std::string &variablesName = "", int indexBase = 1);
+
+    /*
+     * As "readDouble()" but ensures that value in the range [minv,maxv] and
+     * number of digit after the decimal point is in range [minAfterPointDigitCount,maxAfterPointDigitCount]
+     * and number is in the form "[-]digit(s)[.digit(s)]".
+     */
+    double readStrictDouble(double minv, double maxv,
+                            int minAfterPointDigitCount, int maxAfterPointDigitCount,
+                            const std::string &variableName = "");
+
+    std::vector<double> readStrictDoubles(int size, double minv, double maxv,
+                                          int minAfterPointDigitCount, int maxAfterPointDigitCount,
+                                          const std::string &variablesName = "", int indexBase = 1);
+
+    /* As readLine(). */
+    std::string readString();
+
+    /* Read many lines. */
+    std::vector<std::string> readStrings(int size, int indexBase = 1);
+
+    /* See readLine(). */
+    void readStringTo(std::string &result);
+
+    /* The same as "readLine()/readString()", but ensures that line matches to the given pattern. */
+    std::string readString(const pattern &p, const std::string &variableName = "");
+
+    /* The same as "readLine()/readString()", but ensures that line matches to the given pattern. */
+    std::string readString(const std::string &ptrn, const std::string &variableName = "");
+
+    /* Read many lines. */
+    std::vector<std::string>
+    readStrings(int size, const pattern &p, const std::string &variableName = "", int indexBase = 1);
+
+    /* Read many lines. */
+    std::vector<std::string>
+    readStrings(int size, const std::string &ptrn, const std::string &variableName = "", int indexBase = 1);
+
+    /* The same as "readLine()/readString()", but ensures that line matches to the given pattern. */
+    void readStringTo(std::string &result, const pattern &p, const std::string &variableName = "");
+
+    /* The same as "readLine()/readString()", but ensures that line matches to the given pattern. */
+    void readStringTo(std::string &result, const std::string &ptrn, const std::string &variableName = "");
+
+    /*
+     * Reads line from the current position to EOLN or EOF. Moves stream pointer to
+     * the first character of the new line (if possible).
+     */
+    std::string readLine();
+
+    /* Read many lines. */
+    std::vector<std::string> readLines(int size, int indexBase = 1);
+
+    /* See readLine(). */
+    void readLineTo(std::string &result);
+
+    /* The same as "readLine()", but ensures that line matches to the given pattern. */
+    std::string readLine(const pattern &p, const std::string &variableName = "");
+
+    /* The same as "readLine()", but ensures that line matches to the given pattern. */
+    std::string readLine(const std::string &ptrn, const std::string &variableName = "");
+
+    /* Read many lines. */
+    std::vector<std::string>
+    readLines(int size, const pattern &p, const std::string &variableName = "", int indexBase = 1);
+
+    /* Read many lines. */
+    std::vector<std::string>
+    readLines(int size, const std::string &ptrn, const std::string &variableName = "", int indexBase = 1);
+
+    /* The same as "readLine()", but ensures that line matches to the given pattern. */
+    void readLineTo(std::string &result, const pattern &p, const std::string &variableName = "");
+
+    /* The same as "readLine()", but ensures that line matches to the given pattern. */
+    void readLineTo(std::string &result, const std::string &ptrn, const std::string &variableName = "");
+
+    /* Reads EOLN or fails. Use it in validators. Calls "eoln()" method internally. */
+    void readEoln();
+
+    /* Reads EOF or fails. Use it in validators. Calls "eof()" method internally. */
+    void readEof();
+
+    /*
+     * Quit-functions aborts program with <result> and <message>:
+     * input/answer streams replace any result to FAIL.
+     */
+    NORETURN void quit(TResult result, const char *msg);
+    /*
+     * Quit-functions aborts program with <result> and <message>:
+     * input/answer streams replace any result to FAIL.
+     */
+    NORETURN void quitf(TResult result, const char *msg, ...);
+
+    /*
+     * Quit-functions aborts program with <result> and <message>:
+     * input/answer streams replace any result to FAIL.
+     */
+    void quitif(bool condition, TResult result, const char *msg, ...);
+    /*
+     * Quit-functions aborts program with <result> and <message>:
+     * input/answer streams replace any result to FAIL.
+     */
+    NORETURN void quits(TResult result, std::string msg);
+
+    /*
+     * Checks condition and aborts a program if condition is false.
+     * Returns _wa for ouf and _fail on any other streams.
+     */
+#ifdef __GNUC__
+    __attribute__ ((format (printf, 3, 4)))
+#endif
+    void ensuref(bool cond, const char *format, ...);
+
+    void __testlib_ensure(bool cond, std::string message);
+
+    void close();
+
+    const static int NO_INDEX = INT_MAX;
+    const static char OPEN_BRACKET = char(11);
+    const static char CLOSE_BRACKET = char(17);
+
+    const static WORD LightGray = 0x07;
+    const static WORD LightRed = 0x0c;
+    const static WORD LightCyan = 0x0b;
+    const static WORD LightGreen = 0x0a;
+    const static WORD LightYellow = 0x0e;
+
+    static void textColor(WORD color);
+
+    static void quitscr(WORD color, const char *msg);
+
+    static void quitscrS(WORD color, std::string msg);
+
+    void xmlSafeWrite(std::FILE *file, const char *msg);
+
+    /* Skips UTF-8 Byte Order Mark. */
+    void skipBom();
+
+private:
+    InStream(const InStream &);
+
+    InStream &operator=(const InStream &);
+};
+
+InStream inf;
+InStream ouf;
+InStream ans;
+bool appesMode;
+std::string appesModeEncoding = "windows-1251";
+std::string resultName;
+std::string checkerName = "untitled checker";
+random_t rnd;
+TTestlibMode testlibMode = _unknown;
+double __testlib_points = std::numeric_limits<float>::infinity();
+
+const size_t VALIDATOR_MAX_VARIABLE_COUNT = 255;
+
+struct ValidatorBoundsHit {
+    static const double EPS;
+    bool minHit;
+    bool maxHit;
+
+    ValidatorBoundsHit(bool minHit = false, bool maxHit = false) : minHit(minHit), maxHit(maxHit) {
+    };
+
+    ValidatorBoundsHit merge(const ValidatorBoundsHit &validatorBoundsHit, bool ignoreMinBound, bool ignoreMaxBound) {
+        return ValidatorBoundsHit(
+                __testlib_max(minHit, validatorBoundsHit.minHit) || ignoreMinBound,
+                __testlib_max(maxHit, validatorBoundsHit.maxHit) || ignoreMaxBound
+        );
+    }
+};
+
+struct ConstantBound {
+    std::string value;
+    bool broken;
+
+    template<typename T>
+    void adjust(T t) {
+        std::string t_string = std::to_string(t);
+        if (t_string.length() >= 32) {
+            broken = true;
+            value = "";
+        } else {
+            if (!broken && value.empty())
+                value = t_string;
+            if (!broken && value != t_string) {
+                broken = true;
+                value = "";
+            }
+        }
+    }
+
+    bool has_value() {
+        return !value.empty() && !broken && value.length() < 32;
+    }
+};
+
+struct ConstantBounds {
+    ConstantBound lowerBound;
+    ConstantBound upperBound;
+};
+
+const double ValidatorBoundsHit::EPS = 1E-12;
+
+class Validator {
+private:
+    const static std::string TEST_MARKUP_HEADER;
+    const static std::string TEST_CASE_OPEN_TAG;
+    const static std::string TEST_CASE_CLOSE_TAG;
+
+    bool _initialized;
+    std::string _testset;
+    std::string _group;
+
+    std::string _testOverviewLogFileName;
+    std::string _testMarkupFileName;
+    int _testCase = -1;
+    std::string _testCaseFileName;
+
+    std::map<std::string, ValidatorBoundsHit> _boundsHitByVariableName;
+    std::map<std::string, ConstantBounds> _constantBoundsByVariableName;
+    std::set<std::string> _features;
+    std::set<std::string> _hitFeatures;
+    std::set<std::string> _variables;
+
+    bool isVariableNameBoundsAnalyzable(const std::string &variableName) {
+        for (size_t i = 0; i < variableName.length(); i++)
+            if ((variableName[i] >= '0' && variableName[i] <= '9') || variableName[i] < ' ')
+                return false;
+        return true;
+    }
+
+    bool isFeatureNameAnalyzable(const std::string &featureName) {
+        for (size_t i = 0; i < featureName.length(); i++)
+            if (featureName[i] < ' ')
+                return false;
+        return true;
+    }
+
+public:
+    Validator() : _initialized(false), _testset("tests"), _group() {
+    }
+
+    void initialize() {
+        _initialized = true;
+    }
+
+    std::string testset() const {
+        if (!_initialized)
+            __testlib_fail("Validator should be initialized with registerValidation(argc, argv) instead of registerValidation() to support validator.testset()");
+        return _testset;
+    }
+
+    std::string group() const {
+        if (!_initialized)
+            __testlib_fail("Validator should be initialized with registerValidation(argc, argv) instead of registerValidation() to support validator.group()");
+        return _group;
+    }
+
+    std::string testOverviewLogFileName() const {
+        return _testOverviewLogFileName;
+    }
+
+    std::string testMarkupFileName() const {
+        return _testMarkupFileName;
+    }
+
+    int testCase() const {
+        return _testCase;
+    }
+
+    std::string testCaseFileName() const {
+        return _testCaseFileName;
+    }
+
+    void setTestset(const char *const testset) {
+        _testset = testset;
+    }
+
+    void setGroup(const char *const group) {
+        _group = group;
+    }
+
+    void setTestOverviewLogFileName(const char *const testOverviewLogFileName) {
+        _testOverviewLogFileName = testOverviewLogFileName;
+    }
+
+    void setTestMarkupFileName(const char *const testMarkupFileName) {
+        _testMarkupFileName = testMarkupFileName;
+    }
+
+    void setTestCase(int testCase) {
+        _testCase = testCase;
+    }
+
+    void setTestCaseFileName(const char *const testCaseFileName) {
+        _testCaseFileName = testCaseFileName;
+    }
+
+    std::string prepVariableName(const std::string &variableName) {
+        if (variableName.length() >= 2 && variableName != "~~") {
+            if (variableName[0] == '~' && variableName.back() != '~')
+                return variableName.substr(1);
+            if (variableName[0] != '~' && variableName.back() == '~')
+                return variableName.substr(0, variableName.length() - 1);
+            if (variableName[0] == '~' && variableName.back() == '~')
+                return variableName.substr(1, variableName.length() - 2);
+        }
+        return variableName;
+    }
+
+    bool ignoreMinBound(const std::string &variableName) {
+        return variableName.length() >= 2 && variableName != "~~" && variableName[0] == '~';
+    }
+
+    bool ignoreMaxBound(const std::string &variableName) {
+        return variableName.length() >= 2 && variableName != "~~" && variableName.back() == '~';
+    }
+
+    void addBoundsHit(const std::string &variableName, ValidatorBoundsHit boundsHit) {
+        if (isVariableNameBoundsAnalyzable(variableName)
+                && _boundsHitByVariableName.size() < VALIDATOR_MAX_VARIABLE_COUNT) {
+            std::string preparedVariableName = prepVariableName(variableName);
+            _boundsHitByVariableName[preparedVariableName] = boundsHit.merge(_boundsHitByVariableName[preparedVariableName],
+                ignoreMinBound(variableName), ignoreMaxBound(variableName));
+        }
+    }
+
+    void addVariable(const std::string &variableName) {
+        if (isVariableNameBoundsAnalyzable(variableName)
+                && _variables.size() < VALIDATOR_MAX_VARIABLE_COUNT) {
+            std::string preparedVariableName = prepVariableName(variableName);
+            _variables.insert(preparedVariableName);
+        }
+    }
+
+    std::string getVariablesLog() {
+        std::string result;
+        for (const std::string &variableName: _variables)
+            result += "variable \"" + variableName + "\"\n";
+        return result;
+    }
+
+    template<typename T>
+    void adjustConstantBounds(const std::string &variableName, T lower, T upper) {
+        if (isVariableNameBoundsAnalyzable(variableName)
+                && _constantBoundsByVariableName.size() < VALIDATOR_MAX_VARIABLE_COUNT) {
+            std::string preparedVariableName = prepVariableName(variableName);
+            _constantBoundsByVariableName[preparedVariableName].lowerBound.adjust(lower);
+            _constantBoundsByVariableName[preparedVariableName].upperBound.adjust(upper);
+        }
+    }
+
+    std::string getBoundsHitLog() {
+        std::string result;
+        for (std::map<std::string, ValidatorBoundsHit>::iterator i = _boundsHitByVariableName.begin();
+             i != _boundsHitByVariableName.end();
+             i++) {
+            result += "\"" + i->first + "\":";
+            if (i->second.minHit)
+                result += " min-value-hit";
+            if (i->second.maxHit)
+                result += " max-value-hit";
+            result += "\n";
+        }
+        return result;
+    }
+
+    std::string getConstantBoundsLog() {
+        std::string result;
+        for (std::map<std::string, ConstantBounds>::iterator i = _constantBoundsByVariableName.begin();
+             i != _constantBoundsByVariableName.end();
+             i++) {
+            if (i->second.lowerBound.has_value() || i->second.upperBound.has_value()) {
+                result += "constant-bounds \"" + i->first + "\":";
+                if (i->second.lowerBound.has_value())
+                    result += " " + i->second.lowerBound.value;
+                else
+                    result += " ?";
+                if (i->second.upperBound.has_value())
+                    result += " " + i->second.upperBound.value;
+                else
+                    result += " ?";
+                result += "\n";
+            }
+        }
+        return result;
+    }
+
+    std::string getFeaturesLog() {
+        std::string result;
+        for (std::set<std::string>::iterator i = _features.begin();
+             i != _features.end();
+             i++) {
+            result += "feature \"" + *i + "\":";
+            if (_hitFeatures.count(*i))
+                result += " hit";
+            result += "\n";
+        }
+        return result;
+    }
+
+    void writeTestOverviewLog() {
+        if (!_testOverviewLogFileName.empty()) {
+            std::string fileName(_testOverviewLogFileName);
+            _testOverviewLogFileName = "";
+
+            FILE* f;
+            bool standard_file = false;
+            if (fileName == "stdout")
+                f = stdout, standard_file = true;
+            else if (fileName == "stderr")
+                f = stderr, standard_file = true;
+            else {
+                f = testlib_fopen_(fileName.c_str(), "wb");
+                if (NULL == f)
+                    __testlib_fail("Validator::writeTestOverviewLog: can't write test overview log to (" + fileName + ")");
+            }
+            fprintf(f, "%s%s%s%s",
+                getBoundsHitLog().c_str(),
+                getFeaturesLog().c_str(),
+                getConstantBoundsLog().c_str(),
+                getVariablesLog().c_str());
+            std::fflush(f);
+            if (!standard_file)
+                if (std::fclose(f))
+                    __testlib_fail("Validator::writeTestOverviewLog: can't close test overview log file (" + fileName + ")");
+        }
+    }
+
+    void writeTestMarkup() {
+        if (!_testMarkupFileName.empty()) {
+            std::vector<int> readChars = inf.getReadChars();
+            if (!readChars.empty()) {
+                std::string markup(TEST_MARKUP_HEADER);
+                for (size_t i = 0; i < readChars.size(); i++) {
+                    int c = readChars[i];
+                    if (i + 1 == readChars.size() && c == -1)
+                        continue;
+                    if (c <= 256) {
+                        char cc = char(c);
+                        if (cc == '\\' || cc == '!')
+                            markup += '\\';
+                        markup += cc;
+                    } else {
+                        markup += TEST_CASE_OPEN_TAG;
+                        markup += toString(c - 256);
+                        markup += TEST_CASE_CLOSE_TAG;
+                    }
+                }
+                FILE* f;
+                bool standard_file = false;
+                if (_testMarkupFileName == "stdout")
+                    f = stdout, standard_file = true;
+                else if (_testMarkupFileName == "stderr")
+                    f = stderr, standard_file = true;
+                else {
+                    f = testlib_fopen_(_testMarkupFileName.c_str(), "wb");
+                    if (NULL == f)
+                        __testlib_fail("Validator::writeTestMarkup: can't write test markup to (" + _testMarkupFileName + ")");
+                }
+                std::fprintf(f, "%s", markup.c_str());
+                std::fflush(f);
+                if (!standard_file)
+                    if (std::fclose(f))
+                        __testlib_fail("Validator::writeTestMarkup: can't close test markup file (" + _testCaseFileName + ")");
+            }
+        }
+    }
+
+    void writeTestCase() {
+        if (_testCase > 0) {
+            std::vector<int> readChars = inf.getReadChars();
+            if (!readChars.empty()) {
+                std::string content, testCaseContent;
+                bool matchedTestCase = false;
+                for (size_t i = 0; i < readChars.size(); i++) {
+                    int c = readChars[i];
+                    if (i + 1 == readChars.size() && c == -1)
+                        continue;
+                    if (c <= 256)
+                        content += char(c);
+                    else {
+                        if (matchedTestCase) {
+                            testCaseContent = content;
+                            matchedTestCase = false;
+                        }
+                        content = "";
+                        int testCase = c - 256;
+                        if (testCase == _testCase)
+                            matchedTestCase = true;
+                    }
+                }
+                if (matchedTestCase)
+                    testCaseContent = content;
+
+                if (!testCaseContent.empty()) {
+                    FILE* f;
+                    bool standard_file = false;
+                    if (_testCaseFileName.empty() || _testCaseFileName == "stdout")
+                        f = stdout, standard_file = true;
+                    else if (_testCaseFileName == "stderr")
+                        f = stderr, standard_file = true;
+                    else {
+                        f = testlib_fopen_(_testCaseFileName.c_str(), "wb");
+                        if (NULL == f)
+                            __testlib_fail("Validator::writeTestCase: can't write test case to (" + _testCaseFileName + ")");
+                    }
+                    std::fprintf(f, "%s", testCaseContent.c_str());
+                    std::fflush(f);
+                    if (!standard_file)
+                        if (std::fclose(f))
+                            __testlib_fail("Validator::writeTestCase: can't close test case file (" + _testCaseFileName + ")");
+                }
+            }
+        }
+    }
+
+    void addFeature(const std::string &feature) {
+        if (_features.count(feature))
+            __testlib_fail("Feature " + feature + " registered twice.");
+        if (!isFeatureNameAnalyzable(feature))
+            __testlib_fail("Feature name '" + feature + "' contains restricted characters.");
+
+        _features.insert(feature);
+    }
+
+    void feature(const std::string &feature) {
+        if (!isFeatureNameAnalyzable(feature))
+            __testlib_fail("Feature name '" + feature + "' contains restricted characters.");
+
+        if (!_features.count(feature))
+            __testlib_fail("Feature " + feature + " didn't registered via addFeature(feature).");
+
+        _hitFeatures.insert(feature);
+    }
+} validator;
+
+const std::string Validator::TEST_MARKUP_HEADER = "MU\xF3\x01";
+const std::string Validator::TEST_CASE_OPEN_TAG = "!c";
+const std::string Validator::TEST_CASE_CLOSE_TAG = ";";
+
+struct TestlibFinalizeGuard {
+    static bool alive;
+    static bool registered;
+
+    int quitCount, readEofCount;
+
+    TestlibFinalizeGuard() : quitCount(0), readEofCount(0) {
+        // No operations.
+    }
+
+    ~TestlibFinalizeGuard() {
+        bool _alive = alive;
+        alive = false;
+
+        if (_alive) {
+            if (testlibMode == _checker && quitCount == 0)
+                __testlib_fail("Checker must end with quit or quitf call.");
+
+            if (testlibMode == _validator && readEofCount == 0 && quitCount == 0)
+                __testlib_fail("Validator must end with readEof call.");
+
+            /* opts */
+            autoEnsureNoUnusedOpts();
+
+            if (!registered)
+                __testlib_fail("Call register-function in the first line of the main (registerTestlibCmd or other similar)");
+        }
+
+        if (__testlib_exitCode == 0) {
+            validator.writeTestOverviewLog();
+            validator.writeTestMarkup();
+            validator.writeTestCase();
+        }
+    }
+
+private:
+    /* opts */
+    void autoEnsureNoUnusedOpts();
+};
+
+bool TestlibFinalizeGuard::alive = true;
+bool TestlibFinalizeGuard::registered = false;
+extern TestlibFinalizeGuard testlibFinalizeGuard;
+
+/*
+ * Call it to disable checks on finalization.
+ */
+void disableFinalizeGuard() {
+    TestlibFinalizeGuard::alive = false;
+}
+
+/* Interactor streams.
+ */
+std::fstream tout;
+
+/* implementation
+ */
+
+InStream::InStream() {
+    reader = NULL;
+    lastLine = -1;
+    opened = false;
+    name = "";
+    mode = _input;
+    strict = false;
+    stdfile = false;
+    wordReserveSize = 4;
+    readManyIteration = NO_INDEX;
+    maxFileSize = 128 * 1024 * 1024; // 128MB.
+    maxTokenLength = 32 * 1024 * 1024; // 32MB.
+    maxMessageLength = 32000;
+}
+
+InStream::InStream(const InStream &baseStream, std::string content) {
+    reader = new StringInputStreamReader(content);
+    lastLine = -1;
+    opened = true;
+    strict = baseStream.strict;
+    stdfile = false;
+    mode = baseStream.mode;
+    name = "based on " + baseStream.name;
+    readManyIteration = NO_INDEX;
+    maxFileSize = 128 * 1024 * 1024; // 128MB.
+    maxTokenLength = 32 * 1024 * 1024; // 32MB.
+    maxMessageLength = 32000;
+}
+
+InStream::~InStream() {
+    if (NULL != reader) {
+        reader->close();
+        delete reader;
+        reader = NULL;
+    }
+}
+
+void InStream::setTestCase(int testCase) {
+    if (testlibMode != _validator || mode != _input || !stdfile || this != &inf)
+        __testlib_fail("InStream::setTestCase can be used only for inf in validator-mode."
+            " Actually, prefer setTestCase function instead of InStream member");
+    reader->setTestCase(testCase);
+}
+
+std::vector<int> InStream::getReadChars() {
+    if (testlibMode != _validator || mode != _input || !stdfile || this != &inf)
+        __testlib_fail("InStream::getReadChars can be used only for inf in validator-mode.");
+    return reader == NULL ? std::vector<int>() : reader->getReadChars();
+}
+
+void setTestCase(int testCase) {
+    static bool first_run = true;
+    static bool zero_based = false;
+
+    if (first_run && testCase == 0)
+        zero_based = true;
+
+    if (zero_based)
+        testCase++;
+
+    __testlib_hasTestCase = true;
+    __testlib_testCase = testCase;
+
+    if (testlibMode == _validator)
+        inf.setTestCase(testCase);
+
+    first_run = false;
+}
+
+#ifdef __GNUC__
+__attribute__((const))
+#endif
+int resultExitCode(TResult r) {
+    if (r == _ok)
+        return OK_EXIT_CODE;
+    if (r == _wa)
+        return WA_EXIT_CODE;
+    if (r == _pe)
+        return PE_EXIT_CODE;
+    if (r == _fail)
+        return FAIL_EXIT_CODE;
+    if (r == _dirt)
+        return DIRT_EXIT_CODE;
+    if (r == _points)
+        return POINTS_EXIT_CODE;
+    if (r == _unexpected_eof)
+#ifdef ENABLE_UNEXPECTED_EOF
+        return UNEXPECTED_EOF_EXIT_CODE;
+#else
+        return PE_EXIT_CODE;
+#endif
+    if (r >= _partially)
+        return PC_BASE_EXIT_CODE + (r - _partially);
+    return FAIL_EXIT_CODE;
+}
+
+void InStream::textColor(
+#if !(defined(ON_WINDOWS) && (!defined(_MSC_VER) || _MSC_VER > 1400)) && defined(__GNUC__)
+        __attribute__((unused))
+#endif
+        WORD color
+) {
+#if defined(ON_WINDOWS) && (!defined(_MSC_VER) || _MSC_VER > 1400)
+    HANDLE handle = GetStdHandle(STD_OUTPUT_HANDLE);
+    SetConsoleTextAttribute(handle, color);
+#endif
+#if !defined(ON_WINDOWS) && defined(__GNUC__)
+    if (isatty(2))
+    {
+        switch (color)
+        {
+        case LightRed:
+            fprintf(stderr, "\033[1;31m");
+            break;
+        case LightCyan:
+            fprintf(stderr, "\033[1;36m");
+            break;
+        case LightGreen:
+            fprintf(stderr, "\033[1;32m");
+            break;
+        case LightYellow:
+            fprintf(stderr, "\033[1;33m");
+            break;
+        case LightGray:
+        default:
+            fprintf(stderr, "\033[0m");
+        }
+    }
+#endif
+}
+
+#ifdef TESTLIB_THROW_EXIT_EXCEPTION_INSTEAD_OF_EXIT
+class exit_exception: public std::exception {
+private:
+    int exitCode;
+public:
+    exit_exception(int exitCode): exitCode(exitCode) {}
+    int getExitCode() { return exitCode; }
+};
+#endif
+
+NORETURN void halt(int exitCode) {
+#ifdef FOOTER
+    InStream::textColor(InStream::LightGray);
+    std::fprintf(stderr, "Checker: \"%s\"\n", checkerName.c_str());
+    std::fprintf(stderr, "Exit code: %d\n", exitCode);
+    InStream::textColor(InStream::LightGray);
+#endif
+    __testlib_exitCode = exitCode;
+#ifdef TESTLIB_THROW_EXIT_EXCEPTION_INSTEAD_OF_EXIT
+    throw exit_exception(exitCode);
+#endif
+    std::exit(exitCode);
+}
+
+static bool __testlib_shouldCheckDirt(TResult result) {
+    return result == _ok || result == _points || result >= _partially;
+}
+
+static std::string __testlib_appendMessage(const std::string &message, const std::string &extra) {
+    int openPos = -1, closePos = -1;
+    for (size_t i = 0; i < message.length(); i++) {
+        if (message[i] == InStream::OPEN_BRACKET) {
+            if (openPos == -1)
+                openPos = int(i);
+            else
+                openPos = INT_MAX;
+        }
+        if (message[i] == InStream::CLOSE_BRACKET) {
+            if (closePos == -1)
+                closePos = int(i);
+            else
+                closePos = INT_MAX;
+        }
+    }
+    if (openPos != -1 && openPos != INT_MAX
+        && closePos != -1 && closePos != INT_MAX
+        && openPos < closePos) {
+        size_t index = message.find(extra, openPos);
+        if (index == std::string::npos || int(index) >= closePos) {
+            std::string result(message);
+            result.insert(closePos, ", " + extra);
+            return result;
+        }
+        return message;
+    }
+
+    return message + " " + InStream::OPEN_BRACKET + extra + InStream::CLOSE_BRACKET;
+}
+
+static std::string __testlib_toPrintableMessage(const std::string &message) {
+    int openPos = -1, closePos = -1;
+    for (size_t i = 0; i < message.length(); i++) {
+        if (message[i] == InStream::OPEN_BRACKET) {
+            if (openPos == -1)
+                openPos = int(i);
+            else
+                openPos = INT_MAX;
+        }
+        if (message[i] == InStream::CLOSE_BRACKET) {
+            if (closePos == -1)
+                closePos = int(i);
+            else
+                closePos = INT_MAX;
+        }
+    }
+    if (openPos != -1 && openPos != INT_MAX
+        && closePos != -1 && closePos != INT_MAX
+        && openPos < closePos) {
+        std::string result(message);
+        result[openPos] = '(';
+        result[closePos] = ')';
+        return result;
+    }
+
+    return message;
+}
+
+NORETURN void InStream::quit(TResult result, const char *msg) {
+    if (TestlibFinalizeGuard::alive)
+        testlibFinalizeGuard.quitCount++;
+
+    std::string message(msg);
+    message = trim(message);
+
+    if (__testlib_hasTestCase) {
+        if (result != _ok)
+            message = __testlib_appendMessage(message, "test case " + vtos(__testlib_testCase));
+        else {
+            if (__testlib_testCase == 1)
+                message = __testlib_appendMessage(message, vtos(__testlib_testCase) + " test case");
+            else
+                message = __testlib_appendMessage(message, vtos(__testlib_testCase) + " test cases");
+        }
+    }
+
+    // You can change maxMessageLength.
+    // Example: 'inf.maxMessageLength = 1024 * 1024;'.
+    if (message.length() > maxMessageLength) {
+        std::string warn = "message length exceeds " + vtos(maxMessageLength)
+                           + ", the message is truncated: ";
+        message = warn + message.substr(0, maxMessageLength - warn.length());
+    }
+
+#ifndef ENABLE_UNEXPECTED_EOF
+    if (result == _unexpected_eof)
+        result = _pe;
+#endif
+
+    if (testlibMode == _scorer && result != _fail)
+        quits(_fail, "Scorer should return points only. Don't use a quit function.");
+
+    if (mode != _output && result != _fail) {
+        if (mode == _input && testlibMode == _validator && lastLine != -1)
+            quits(_fail, __testlib_appendMessage(__testlib_appendMessage(message, name), "line " + vtos(lastLine)));
+        else
+            quits(_fail, __testlib_appendMessage(message, name));
+    }
+
+    std::FILE *resultFile;
+    std::string errorName;
+
+    if (__testlib_shouldCheckDirt(result)) {
+        if (testlibMode != _interactor && !ouf.seekEof())
+            quit(_dirt, "Extra information in the output file");
+    }
+
+    int pctype = result - _partially;
+    bool isPartial = false;
+
+    switch (result) {
+        case _ok:
+            errorName = "ok ";
+            quitscrS(LightGreen, errorName);
+            break;
+        case _wa:
+            errorName = "wrong answer ";
+            quitscrS(LightRed, errorName);
+            break;
+        case _pe:
+            errorName = "wrong output format ";
+            quitscrS(LightRed, errorName);
+            break;
+        case _fail:
+            errorName = "FAIL ";
+            quitscrS(LightRed, errorName);
+            break;
+        case _dirt:
+            errorName = "wrong output format ";
+            quitscrS(LightCyan, errorName);
+            result = _pe;
+            break;
+        case _points:
+            errorName = "points ";
+            quitscrS(LightYellow, errorName);
+            break;
+        case _unexpected_eof:
+            errorName = "unexpected eof ";
+            quitscrS(LightCyan, errorName);
+            break;
+        default:
+            if (result >= _partially) {
+                errorName = testlib_format_("partially correct (%d) ", pctype);
+                isPartial = true;
+                quitscrS(LightYellow, errorName);
+            } else
+                quit(_fail, "What is the code ??? ");
+    }
+
+    if (resultName != "") {
+        resultFile = testlib_fopen_(resultName.c_str(), "w");
+        if (resultFile == NULL) {
+            resultName = "";
+            quit(_fail, "Can not write to the result file");
+        }
+        if (appesMode) {
+            std::fprintf(resultFile, "<?xml version=\"1.0\" encoding=\"%s\"?>", appesModeEncoding.c_str());
+            if (isPartial)
+                std::fprintf(resultFile, "<result outcome = \"%s\" pctype = \"%d\">",
+                             outcomes[(int) _partially].c_str(), pctype);
+            else {
+                if (result != _points)
+                    std::fprintf(resultFile, "<result outcome = \"%s\">", outcomes[(int) result].c_str());
+                else {
+                    if (__testlib_points == std::numeric_limits<float>::infinity())
+                        quit(_fail, "Expected points, but infinity found");
+                    std::string stringPoints = removeDoubleTrailingZeroes(testlib_format_("%.10f", __testlib_points));
+                    std::fprintf(resultFile, "<result outcome = \"%s\" points = \"%s\">",
+                                 outcomes[(int) result].c_str(), stringPoints.c_str());
+                }
+            }
+            xmlSafeWrite(resultFile, __testlib_toPrintableMessage(message).c_str());
+            std::fprintf(resultFile, "</result>\n");
+        } else
+            std::fprintf(resultFile, "%s", __testlib_toPrintableMessage(message).c_str());
+        if (NULL == resultFile || fclose(resultFile) != 0) {
+            resultName = "";
+            quit(_fail, "Can not write to the result file");
+        }
+    }
+
+    quitscr(LightGray, __testlib_toPrintableMessage(message).c_str());
+    std::fprintf(stderr, "\n");
+
+    inf.close();
+    ouf.close();
+    ans.close();
+    if (tout.is_open())
+        tout.close();
+
+    textColor(LightGray);
+
+    if (resultName != "")
+        std::fprintf(stderr, "See file to check exit message\n");
+
+    halt(resultExitCode(result));
+}
+
+#ifdef __GNUC__
+__attribute__ ((format (printf, 3, 4)))
+#endif
+NORETURN void InStream::quitf(TResult result, const char *msg, ...) {
+    FMT_TO_RESULT(msg, msg, message);
+    InStream::quit(result, message.c_str());
+}
+
+#ifdef __GNUC__
+__attribute__ ((format (printf, 4, 5)))
+#endif
+void InStream::quitif(bool condition, TResult result, const char *msg, ...) {
+    if (condition) {
+        FMT_TO_RESULT(msg, msg, message);
+        InStream::quit(result, message.c_str());
+    }
+}
+
+NORETURN void InStream::quits(TResult result, std::string msg) {
+    InStream::quit(result, msg.c_str());
+}
+
+void InStream::xmlSafeWrite(std::FILE *file, const char *msg) {
+    size_t lmsg = strlen(msg);
+    for (size_t i = 0; i < lmsg; i++) {
+        if (msg[i] == '&') {
+            std::fprintf(file, "%s", "&amp;");
+            continue;
+        }
+        if (msg[i] == '<') {
+            std::fprintf(file, "%s", "&lt;");
+            continue;
+        }
+        if (msg[i] == '>') {
+            std::fprintf(file, "%s", "&gt;");
+            continue;
+        }
+        if (msg[i] == '"') {
+            std::fprintf(file, "%s", "&quot;");
+            continue;
+        }
+        if (0 <= msg[i] && msg[i] <= 31) {
+            std::fprintf(file, "%c", '.');
+            continue;
+        }
+        std::fprintf(file, "%c", msg[i]);
+    }
+}
+
+void InStream::quitscrS(WORD color, std::string msg) {
+    quitscr(color, msg.c_str());
+}
+
+void InStream::quitscr(WORD color, const char *msg) {
+    if (resultName == "") {
+        textColor(color);
+        std::fprintf(stderr, "%s", msg);
+        textColor(LightGray);
+    }
+}
+
+void InStream::reset(std::FILE *file) {
+    if (opened && stdfile)
+        quit(_fail, "Can't reset standard handle");
+
+    if (opened)
+        close();
+
+    if (!stdfile && NULL == file)
+        if (NULL == (file = testlib_fopen_(name.c_str(), "rb"))) {
+            if (mode == _output)
+                quits(_pe, std::string("Output file not found: \"") + name + "\"");
+
+            if (mode == _answer)
+                quits(_fail, std::string("Answer file not found: \"") + name + "\"");
+        }
+
+    if (NULL != file) {
+        opened = true;
+        __testlib_set_binary(file);
+
+        if (stdfile)
+            reader = new FileInputStreamReader(file, name);
+        else
+            reader = new BufferedFileInputStreamReader(file, name);
+    } else {
+        opened = false;
+        reader = NULL;
+    }
+}
+
+void InStream::init(std::string fileName, TMode mode) {
+    opened = false;
+    name = fileName;
+    stdfile = false;
+    this->mode = mode;
+
+    std::ifstream stream;
+    stream.open(fileName.c_str(), std::ios::in);
+    if (stream.is_open()) {
+        std::streampos start = stream.tellg();
+        stream.seekg(0, std::ios::end);
+        std::streampos end = stream.tellg();
+        size_t fileSize = size_t(end - start);
+        stream.close();
+
+        // You can change maxFileSize.
+        // Example: 'inf.maxFileSize = 256 * 1024 * 1024;'.
+        if (fileSize > maxFileSize)
+            quitf(_pe, "File size exceeds %d bytes, size is %d", int(maxFileSize), int(fileSize));
+    }
+
+    reset();
+}
+
+void InStream::init(std::FILE *f, TMode mode) {
+    opened = false;
+    name = "untitled";
+    this->mode = mode;
+
+    if (f == stdin)
+        name = "stdin", stdfile = true;
+    if (f == stdout)
+        name = "stdout", stdfile = true;
+    if (f == stderr)
+        name = "stderr", stdfile = true;
+
+    reset(f);
+}
+
+void InStream::skipBom() {
+    const std::string utf8Bom = "\xEF\xBB\xBF";
+    size_t index = 0;
+    while (index < utf8Bom.size() && curChar() == utf8Bom[index]) {
+        index++;
+        skipChar();
+    }
+    if (index < utf8Bom.size()) {
+        while (index != 0) {
+            unreadChar(utf8Bom[index - 1]);
+            index--;
+        }
+    }
+}
+
+char InStream::curChar() {
+    return char(reader->curChar());
+}
+
+char InStream::nextChar() {
+    return char(reader->nextChar());
+}
+
+char InStream::readChar() {
+    return nextChar();
+}
+
+char InStream::readChar(char c) {
+    lastLine = reader->getLine();
+    char found = readChar();
+    if (c != found) {
+        if (!isEoln(found))
+            quit(_pe, ("Unexpected character '" + std::string(1, found) + "', but '" + std::string(1, c) +
+                       "' expected").c_str());
+        else
+            quit(_pe, ("Unexpected character " + ("#" + vtos(int(found))) + ", but '" + std::string(1, c) +
+                       "' expected").c_str());
+    }
+    return found;
+}
+
+char InStream::readSpace() {
+    return readChar(' ');
+}
+
+void InStream::unreadChar(char c) {
+    reader->unreadChar(c);
+}
+
+void InStream::skipChar() {
+    reader->skipChar();
+}
+
+void InStream::skipBlanks() {
+    while (isBlanks(reader->curChar()))
+        reader->skipChar();
+}
+
+std::string InStream::readWord() {
+    readWordTo(_tmpReadToken);
+    return _tmpReadToken;
+}
+
+void InStream::readWordTo(std::string &result) {
+    if (!strict)
+        skipBlanks();
+
+    lastLine = reader->getLine();
+    int cur = reader->nextChar();
+
+    if (cur == EOFC)
+        quit(_unexpected_eof, "Unexpected end of file - token expected");
+
+    if (isBlanks(cur))
+        quit(_pe, "Unexpected white-space - token expected");
+
+    result.clear();
+
+    while (!(isBlanks(cur) || cur == EOFC)) {
+        result += char(cur);
+
+        // You can change maxTokenLength.
+        // Example: 'inf.maxTokenLength = 128 * 1024 * 1024;'.
+        if (result.length() > maxTokenLength)
+            quitf(_pe, "Length of token exceeds %d, token is '%s...'", int(maxTokenLength),
+                  __testlib_part(result).c_str());
+
+        cur = reader->nextChar();
+    }
+
+    reader->unreadChar(cur);
+
+    if (result.length() == 0)
+        quit(_unexpected_eof, "Unexpected end of file or white-space - token expected");
+}
+
+std::string InStream::readToken() {
+    return readWord();
+}
+
+void InStream::readTokenTo(std::string &result) {
+    readWordTo(result);
+}
+
+#ifdef __GNUC__
+__attribute__((const))
+#endif
+static std::string __testlib_part(const std::string &s) {
+    std::string t;
+    for (size_t i = 0; i < s.length(); i++)
+        if (s[i] != '\0')
+            t += s[i];
+        else
+            t += '~';
+    if (t.length() <= 64)
+        return t;
+    else
+        return t.substr(0, 30) + "..." + t.substr(s.length() - 31, 31);
+}
+
+#define __testlib_readMany(readMany, readOne, typeName, space)                  \
+    if (size < 0)                                                               \
+        quit(_fail, #readMany ": size should be non-negative.");                \
+    if (size > 100000000)                                                       \
+        quit(_fail, #readMany ": size should be at most 100000000.");           \
+                                                                                \
+    std::vector<typeName> result(size);                                         \
+    readManyIteration = indexBase;                                              \
+                                                                                \
+    for (int i = 0; i < size; i++)                                              \
+    {                                                                           \
+        result[i] = readOne;                                                    \
+        readManyIteration++;                                                    \
+        if (strict && space && i + 1 < size)                                              \
+            readSpace();                                                        \
+    }                                                                           \
+                                                                                \
+    readManyIteration = NO_INDEX;                                               \
+    return result;                                                              \
+
+
+std::string InStream::readWord(const pattern &p, const std::string &variableName) {
+    readWordTo(_tmpReadToken);
+    if (!p.matches(_tmpReadToken)) {
+        if (readManyIteration == NO_INDEX) {
+            if (variableName.empty())
+                quit(_wa,
+                     ("Token \"" + __testlib_part(_tmpReadToken) + "\" doesn't correspond to pattern \"" + p.src() +
+                      "\"").c_str());
+            else
+                quit(_wa, ("Token parameter [name=" + variableName + "] equals to \"" + __testlib_part(_tmpReadToken) +
+                           "\", doesn't correspond to pattern \"" + p.src() + "\"").c_str());
+        } else {
+            if (variableName.empty())
+                quit(_wa, ("Token element [index=" + vtos(readManyIteration) + "] equals to \"" +
+                           __testlib_part(_tmpReadToken) + "\" doesn't correspond to pattern \"" + p.src() +
+                           "\"").c_str());
+            else
+                quit(_wa, ("Token element " + variableName + "[" + vtos(readManyIteration) + "] equals to \"" +
+                           __testlib_part(_tmpReadToken) + "\", doesn't correspond to pattern \"" + p.src() +
+                           "\"").c_str());
+        }
+    }
+    if (strict && !variableName.empty())
+        validator.addVariable(variableName);
+    return _tmpReadToken;
+}
+
+std::vector<std::string>
+InStream::readWords(int size, const pattern &p, const std::string &variablesName, int indexBase) {
+    if (strict && !variablesName.empty())
+        validator.addVariable(variablesName);
+    __testlib_readMany(readWords, readWord(p, variablesName), std::string, true);
+}
+
+std::vector<std::string> InStream::readWords(int size, int indexBase) {
+    __testlib_readMany(readWords, readWord(), std::string, true);
+}
+
+std::string InStream::readWord(const std::string &ptrn, const std::string &variableName) {
+    return readWord(pattern(ptrn), variableName);
+}
+
+std::vector<std::string>
+InStream::readWords(int size, const std::string &ptrn, const std::string &variablesName, int indexBase) {
+    pattern p(ptrn);
+    if (strict && !variablesName.empty())
+        validator.addVariable(variablesName);
+    __testlib_readMany(readWords, readWord(p, variablesName), std::string, true);
+}
+
+std::string InStream::readToken(const pattern &p, const std::string &variableName) {
+    return readWord(p, variableName);
+}
+
+std::vector<std::string>
+InStream::readTokens(int size, const pattern &p, const std::string &variablesName, int indexBase) {
+    if (strict && !variablesName.empty())
+        validator.addVariable(variablesName);
+    __testlib_readMany(readTokens, readToken(p, variablesName), std::string, true);
+}
+
+std::vector<std::string> InStream::readTokens(int size, int indexBase) {
+    __testlib_readMany(readTokens, readToken(), std::string, true);
+}
+
+std::string InStream::readToken(const std::string &ptrn, const std::string &variableName) {
+    return readWord(ptrn, variableName);
+}
+
+std::vector<std::string>
+InStream::readTokens(int size, const std::string &ptrn, const std::string &variablesName, int indexBase) {
+    pattern p(ptrn);
+    if (strict && !variablesName.empty())
+        validator.addVariable(variablesName);
+    __testlib_readMany(readTokens, readWord(p, variablesName), std::string, true);
+}
+
+void InStream::readWordTo(std::string &result, const pattern &p, const std::string &variableName) {
+    readWordTo(result);
+    if (!p.matches(result)) {
+        if (variableName.empty())
+            quit(_wa, ("Token \"" + __testlib_part(result) + "\" doesn't correspond to pattern \"" + p.src() +
+                       "\"").c_str());
+        else
+            quit(_wa, ("Token parameter [name=" + variableName + "] equals to \"" + __testlib_part(result) +
+                       "\", doesn't correspond to pattern \"" + p.src() + "\"").c_str());
+    }
+    if (strict && !variableName.empty())
+        validator.addVariable(variableName);
+}
+
+void InStream::readWordTo(std::string &result, const std::string &ptrn, const std::string &variableName) {
+    return readWordTo(result, pattern(ptrn), variableName);
+}
+
+void InStream::readTokenTo(std::string &result, const pattern &p, const std::string &variableName) {
+    return readWordTo(result, p, variableName);
+}
+
+void InStream::readTokenTo(std::string &result, const std::string &ptrn, const std::string &variableName) {
+    return readWordTo(result, ptrn, variableName);
+}
+
+#ifdef __GNUC__
+__attribute__((pure))
+#endif
+static inline bool equals(long long integer, const char *s) {
+    if (integer == LLONG_MIN)
+        return strcmp(s, "-9223372036854775808") == 0;
+
+    if (integer == 0LL)
+        return strcmp(s, "0") == 0;
+
+    size_t length = strlen(s);
+
+    if (length == 0)
+        return false;
+
+    if (integer < 0 && s[0] != '-')
+        return false;
+
+    if (integer < 0)
+        s++, length--, integer = -integer;
+
+    if (length == 0)
+        return false;
+
+    while (integer > 0) {
+        int digit = int(integer % 10);
+
+        if (s[length - 1] != '0' + digit)
+            return false;
+
+        length--;
+        integer /= 10;
+    }
+
+    return length == 0;
+}
+
+#ifdef __GNUC__
+__attribute__((pure))
+#endif
+static inline bool equals(unsigned long long integer, const char *s) {
+    if (integer == ULLONG_MAX)
+        return strcmp(s, "18446744073709551615") == 0;
+
+    if (integer == 0ULL)
+        return strcmp(s, "0") == 0;
+
+    size_t length = strlen(s);
+
+    if (length == 0)
+        return false;
+
+    while (integer > 0) {
+        int digit = int(integer % 10);
+
+        if (s[length - 1] != '0' + digit)
+            return false;
+
+        length--;
+        integer /= 10;
+    }
+
+    return length == 0;
+}
+
+static inline double stringToDouble(InStream &in, const char *buffer) {
+    double result;
+
+    size_t length = strlen(buffer);
+
+    int minusCount = 0;
+    int plusCount = 0;
+    int decimalPointCount = 0;
+    int digitCount = 0;
+    int eCount = 0;
+
+    for (size_t i = 0; i < length; i++) {
+        if (('0' <= buffer[i] && buffer[i] <= '9') || buffer[i] == '.'
+            || buffer[i] == 'e' || buffer[i] == 'E'
+            || buffer[i] == '-' || buffer[i] == '+') {
+            if ('0' <= buffer[i] && buffer[i] <= '9')
+                digitCount++;
+            if (buffer[i] == 'e' || buffer[i] == 'E')
+                eCount++;
+            if (buffer[i] == '-')
+                minusCount++;
+            if (buffer[i] == '+')
+                plusCount++;
+            if (buffer[i] == '.')
+                decimalPointCount++;
+        } else
+            in.quit(_pe, ("Expected double, but \"" + __testlib_part(buffer) + "\" found").c_str());
+    }
+
+    // If for sure is not a number in standard notation or in e-notation.
+    if (digitCount == 0 || minusCount > 2 || plusCount > 2 || decimalPointCount > 1 || eCount > 1)
+        in.quit(_pe, ("Expected double, but \"" + __testlib_part(buffer) + "\" found").c_str());
+
+    char *suffix = new char[length + 1];
+    std::memset(suffix, 0, length + 1);
+    int scanned;
+#ifdef _MSC_VER
+    scanned = sscanf_s(buffer, "%lf%s", &result, suffix, (unsigned int)(length + 1));
+#else
+    scanned = std::sscanf(buffer, "%lf%s", &result, suffix);
+#endif
+    bool empty = strlen(suffix) == 0;
+    delete[] suffix;
+
+    if (scanned == 1 || (scanned == 2 && empty)) {
+        if (__testlib_isNaN(result))
+            in.quit(_pe, ("Expected double, but \"" + __testlib_part(buffer) + "\" found").c_str());
+        return result;
+    } else
+        in.quit(_pe, ("Expected double, but \"" + __testlib_part(buffer) + "\" found").c_str());
+}
+
+static inline double stringToDouble(InStream &in, const std::string& buffer) {
+    for (size_t i = 0; i < buffer.length(); i++)
+        if (buffer[i] == '\0')
+            in.quit(_pe, ("Expected double, but \"" + __testlib_part(buffer) + "\" found (it contains \\0)").c_str());
+    return stringToDouble(in, buffer.c_str());
+}
+
+static inline double stringToStrictDouble(InStream &in, const char *buffer,
+        int minAfterPointDigitCount, int maxAfterPointDigitCount) {
+    if (minAfterPointDigitCount < 0)
+        in.quit(_fail, "stringToStrictDouble: minAfterPointDigitCount should be non-negative.");
+
+    if (minAfterPointDigitCount > maxAfterPointDigitCount)
+        in.quit(_fail,
+                "stringToStrictDouble: minAfterPointDigitCount should be less or equal to maxAfterPointDigitCount.");
+
+    double result;
+
+    size_t length = strlen(buffer);
+
+    if (length == 0 || length > 1000)
+        in.quit(_pe, ("Expected strict double, but \"" + __testlib_part(buffer) + "\" found").c_str());
+
+    if (buffer[0] != '-' && (buffer[0] < '0' || buffer[0] > '9'))
+        in.quit(_pe, ("Expected strict double, but \"" + __testlib_part(buffer) + "\" found").c_str());
+
+    int pointPos = -1;
+    for (size_t i = 1; i + 1 < length; i++) {
+        if (buffer[i] == '.') {
+            if (pointPos > -1)
+                in.quit(_pe, ("Expected strict double, but \"" + __testlib_part(buffer) + "\" found").c_str());
+            pointPos = int(i);
+        }
+        if (buffer[i] != '.' && (buffer[i] < '0' || buffer[i] > '9'))
+            in.quit(_pe, ("Expected strict double, but \"" + __testlib_part(buffer) + "\" found").c_str());
+    }
+
+    if (buffer[length - 1] < '0' || buffer[length - 1] > '9')
+        in.quit(_pe, ("Expected strict double, but \"" + __testlib_part(buffer) + "\" found").c_str());
+
+    int afterDigitsCount = (pointPos == -1 ? 0 : int(length) - pointPos - 1);
+    if (afterDigitsCount < minAfterPointDigitCount || afterDigitsCount > maxAfterPointDigitCount)
+        in.quit(_pe, ("Expected strict double with number of digits after point in range ["
+                      + vtos(minAfterPointDigitCount)
+                      + ","
+                      + vtos(maxAfterPointDigitCount)
+                      + "], but \"" + __testlib_part(buffer) + "\" found").c_str()
+        );
+
+    int firstDigitPos = -1;
+    for (size_t i = 0; i < length; i++)
+        if (buffer[i] >= '0' && buffer[i] <= '9') {
+            firstDigitPos = int(i);
+            break;
+        }
+
+    if (firstDigitPos > 1 || firstDigitPos == -1)
+        in.quit(_pe, ("Expected strict double, but \"" + __testlib_part(buffer) + "\" found").c_str());
+
+    if (buffer[firstDigitPos] == '0' && firstDigitPos + 1 < int(length)
+        && buffer[firstDigitPos + 1] >= '0' && buffer[firstDigitPos + 1] <= '9')
+        in.quit(_pe, ("Expected strict double, but \"" + __testlib_part(buffer) + "\" found").c_str());
+
+    char *suffix = new char[length + 1];
+    std::memset(suffix, 0, length + 1);
+    int scanned;
+#ifdef _MSC_VER
+    scanned = sscanf_s(buffer, "%lf%s", &result, suffix, (unsigned int)(length + 1));
+#else
+    scanned = std::sscanf(buffer, "%lf%s", &result, suffix);
+#endif
+    bool empty = strlen(suffix) == 0;
+    delete[] suffix;
+
+    if (scanned == 1 || (scanned == 2 && empty)) {
+        if (__testlib_isNaN(result) || __testlib_isInfinite(result))
+            in.quit(_pe, ("Expected double, but \"" + __testlib_part(buffer) + "\" found").c_str());
+        if (buffer[0] == '-' && result >= 0)
+            in.quit(_pe, ("Redundant minus in \"" + __testlib_part(buffer) + "\" found").c_str());
+        return result;
+    } else
+        in.quit(_pe, ("Expected double, but \"" + __testlib_part(buffer) + "\" found").c_str());
+}
+
+static inline double stringToStrictDouble(InStream &in, const std::string& buffer,
+        int minAfterPointDigitCount, int maxAfterPointDigitCount) {
+    for (size_t i = 0; i < buffer.length(); i++)
+        if (buffer[i] == '\0')
+            in.quit(_pe, ("Expected double, but \"" + __testlib_part(buffer) + "\" found (it contains \\0)").c_str());
+    return stringToStrictDouble(in, buffer.c_str(), minAfterPointDigitCount, maxAfterPointDigitCount);
+}
+
+static inline long long stringToLongLong(InStream &in, const char *buffer) {
+    size_t length = strlen(buffer);
+    if (length == 0 || length > 20)
+        in.quit(_pe, ("Expected integer, but \"" + __testlib_part(buffer) + "\" found").c_str());
+
+    bool has_minus = (length > 1 && buffer[0] == '-');
+    int zeroes = 0;
+    bool processingZeroes = true;
+
+    for (int i = (has_minus ? 1 : 0); i < int(length); i++) {
+        if (buffer[i] == '0' && processingZeroes)
+            zeroes++;
+        else
+            processingZeroes = false;
+
+        if (buffer[i] < '0' || buffer[i] > '9')
+            in.quit(_pe, ("Expected integer, but \"" + __testlib_part(buffer) + "\" found").c_str());
+    }
+
+    long long int result;
+    try {
+        result = std::stoll(buffer);
+    } catch (const std::exception&) {
+        in.quit(_pe, ("Expected integer, but \"" + __testlib_part(buffer) + "\" found").c_str());
+    } catch (...) {
+        in.quit(_pe, ("Expected integer, but \"" + __testlib_part(buffer) + "\" found").c_str());
+    }
+
+    if ((zeroes > 0 && (result != 0 || has_minus)) || zeroes > 1)
+        in.quit(_pe, ("Expected integer, but \"" + __testlib_part(buffer) + "\" found").c_str());
+
+    return result;
+}
+
+static inline long long stringToLongLong(InStream &in, const std::string& buffer) {
+    for (size_t i = 0; i < buffer.length(); i++)
+        if (buffer[i] == '\0')
+            in.quit(_pe, ("Expected integer, but \"" + __testlib_part(buffer) + "\" found (it contains \\0)").c_str());
+    return stringToLongLong(in, buffer.c_str());
+}
+
+static inline unsigned long long stringToUnsignedLongLong(InStream &in, const char *buffer) {
+    size_t length = strlen(buffer);
+
+    if (length == 0 || length > 20)
+        in.quit(_pe, ("Expected unsigned integer, but \"" + __testlib_part(buffer) + "\" found").c_str());
+    if (length > 1 && buffer[0] == '0')
+        in.quit(_pe, ("Expected unsigned integer, but \"" + __testlib_part(buffer) + "\" found").c_str());
+
+    for (int i = 0; i < int(length); i++) {
+        if (buffer[i] < '0' || buffer[i] > '9')
+            in.quit(_pe, ("Expected unsigned integer, but \"" + __testlib_part(buffer) + "\" found").c_str());
+    }
+
+    unsigned long long result;
+    try {
+        result = std::stoull(buffer);
+    } catch (const std::exception&) {
+        in.quit(_pe, ("Expected unsigned integer, but \"" + __testlib_part(buffer) + "\" found").c_str());
+    } catch (...) {
+        in.quit(_pe, ("Expected unsigned integer, but \"" + __testlib_part(buffer) + "\" found").c_str());
+    }
+
+    return result;
+}
+
+static inline long long stringToUnsignedLongLong(InStream &in, const std::string& buffer) {
+    for (size_t i = 0; i < buffer.length(); i++)
+        if (buffer[i] == '\0')
+            in.quit(_pe, ("Expected unsigned integer, but \"" + __testlib_part(buffer) + "\" found (it contains \\0)").c_str());
+    return stringToUnsignedLongLong(in, buffer.c_str());
+}
+
+int InStream::readInteger() {
+    if (!strict && seekEof())
+        quit(_unexpected_eof, "Unexpected end of file - int32 expected");
+
+    readWordTo(_tmpReadToken);
+
+    long long value = stringToLongLong(*this, _tmpReadToken);
+    if (value < INT_MIN || value > INT_MAX)
+        quit(_pe, ("Expected int32, but \"" + __testlib_part(_tmpReadToken) + "\" found").c_str());
+
+    return int(value);
+}
+
+long long InStream::readLong() {
+    if (!strict && seekEof())
+        quit(_unexpected_eof, "Unexpected end of file - int64 expected");
+
+    readWordTo(_tmpReadToken);
+
+    return stringToLongLong(*this, _tmpReadToken);
+}
+
+unsigned long long InStream::readUnsignedLong() {
+    if (!strict && seekEof())
+        quit(_unexpected_eof, "Unexpected end of file - int64 expected");
+
+    readWordTo(_tmpReadToken);
+
+    return stringToUnsignedLongLong(*this, _tmpReadToken);
+}
+
+long long InStream::readLong(long long minv, long long maxv, const std::string &variableName) {
+    long long result = readLong();
+
+    if (result < minv || result > maxv) {
+        if (readManyIteration == NO_INDEX) {
+            if (variableName.empty())
+                quit(_wa, ("Integer " + vtos(result) + " violates the range [" + toHumanReadableString(minv) + ", " + toHumanReadableString(maxv) +
+                           "]").c_str());
+            else
+                quit(_wa, ("Integer parameter [name=" + std::string(variableName) + "] equals to " + vtos(result) +
+                           ", violates the range [" + toHumanReadableString(minv) + ", " + toHumanReadableString(maxv) + "]").c_str());
+        } else {
+            if (variableName.empty())
+                quit(_wa, ("Integer element [index=" + vtos(readManyIteration) + "] equals to " + vtos(result) +
+                           ", violates the range [" + toHumanReadableString(minv) + ", " + toHumanReadableString(maxv) + "]").c_str());
+            else
+                quit(_wa,
+                     ("Integer element " + std::string(variableName) + "[" + vtos(readManyIteration) + "] equals to " +
+                      vtos(result) + ", violates the range [" + toHumanReadableString(minv) + ", " + toHumanReadableString(maxv) + "]").c_str());
+        }
+    }
+
+    if (strict && !variableName.empty()) {
+        validator.addBoundsHit(variableName, ValidatorBoundsHit(minv == result, maxv == result));
+        validator.adjustConstantBounds(variableName, minv, maxv);
+        validator.addVariable(variableName);
+    }
+
+    return result;
+}
+
+std::vector<long long>
+InStream::readLongs(int size, long long minv, long long maxv, const std::string &variablesName, int indexBase) {
+    if (strict && !variablesName.empty())
+        validator.addVariable(variablesName);
+    __testlib_readMany(readLongs, readLong(minv, maxv, variablesName), long long, true)
+}
+
+std::vector<long long> InStream::readLongs(int size, int indexBase) {
+    __testlib_readMany(readLongs, readLong(), long long, true)
+}
+
+unsigned long long
+InStream::readUnsignedLong(unsigned long long minv, unsigned long long maxv, const std::string &variableName) {
+    unsigned long long result = readUnsignedLong();
+
+    if (result < minv || result > maxv) {
+        if (readManyIteration == NO_INDEX) {
+            if (variableName.empty())
+                quit(_wa,
+                     ("Unsigned integer " + vtos(result) + " violates the range [" + toHumanReadableString(minv) + ", " + toHumanReadableString(maxv) +
+                      "]").c_str());
+            else
+                quit(_wa,
+                     ("Unsigned integer parameter [name=" + std::string(variableName) + "] equals to " + vtos(result) +
+                      ", violates the range [" + toHumanReadableString(minv) + ", " + toHumanReadableString(maxv) + "]").c_str());
+        } else {
+            if (variableName.empty())
+                quit(_wa,
+                     ("Unsigned integer element [index=" + vtos(readManyIteration) + "] equals to " + vtos(result) +
+                      ", violates the range [" + toHumanReadableString(minv) + ", " + toHumanReadableString(maxv) + "]").c_str());
+            else
+                quit(_wa, ("Unsigned integer element " + std::string(variableName) + "[" + vtos(readManyIteration) +
+                           "] equals to " + vtos(result) + ", violates the range [" + toHumanReadableString(minv) + ", " + toHumanReadableString(maxv) +
+                           "]").c_str());
+        }
+    }
+
+    if (strict && !variableName.empty()) {
+        validator.addBoundsHit(variableName, ValidatorBoundsHit(minv == result, maxv == result));
+        validator.adjustConstantBounds(variableName, minv, maxv);
+        validator.addVariable(variableName);
+    }
+
+    return result;
+}
+
+std::vector<unsigned long long> InStream::readUnsignedLongs(int size, unsigned long long minv, unsigned long long maxv,
+                                                            const std::string &variablesName, int indexBase) {
+    if (strict && !variablesName.empty())
+        validator.addVariable(variablesName);
+    __testlib_readMany(readUnsignedLongs, readUnsignedLong(minv, maxv, variablesName), unsigned long long, true)
+}
+
+std::vector<unsigned long long> InStream::readUnsignedLongs(int size, int indexBase) {
+    __testlib_readMany(readUnsignedLongs, readUnsignedLong(), unsigned long long, true)
+}
+
+unsigned long long
+InStream::readLong(unsigned long long minv, unsigned long long maxv, const std::string &variableName) {
+    return readUnsignedLong(minv, maxv, variableName);
+}
+
+int InStream::readInt() {
+    return readInteger();
+}
+
+int InStream::readInt(int minv, int maxv, const std::string &variableName) {
+    int result = readInt();
+
+    if (result < minv || result > maxv) {
+        if (readManyIteration == NO_INDEX) {
+            if (variableName.empty())
+                quit(_wa, ("Integer " + vtos(result) + " violates the range [" + toHumanReadableString(minv) + ", " + toHumanReadableString(maxv) +
+                           "]").c_str());
+            else
+                quit(_wa, ("Integer parameter [name=" + std::string(variableName) + "] equals to " + vtos(result) +
+                           ", violates the range [" + toHumanReadableString(minv) + ", " + toHumanReadableString(maxv) + "]").c_str());
+        } else {
+            if (variableName.empty())
+                quit(_wa, ("Integer element [index=" + vtos(readManyIteration) + "] equals to " + vtos(result) +
+                           ", violates the range [" + toHumanReadableString(minv) + ", " + toHumanReadableString(maxv) + "]").c_str());
+            else
+                quit(_wa,
+                     ("Integer element " + std::string(variableName) + "[" + vtos(readManyIteration) + "] equals to " +
+                      vtos(result) + ", violates the range [" + toHumanReadableString(minv) + ", " + toHumanReadableString(maxv) + "]").c_str());
+        }
+    }
+
+    if (strict && !variableName.empty()) {
+        validator.addBoundsHit(variableName, ValidatorBoundsHit(minv == result, maxv == result));
+        validator.adjustConstantBounds(variableName, minv, maxv);
+        validator.addVariable(variableName);
+    }
+
+    return result;
+}
+
+int InStream::readInteger(int minv, int maxv, const std::string &variableName) {
+    return readInt(minv, maxv, variableName);
+}
+
+std::vector<int> InStream::readInts(int size, int minv, int maxv, const std::string &variablesName, int indexBase) {
+    if (strict && !variablesName.empty())
+        validator.addVariable(variablesName);
+    __testlib_readMany(readInts, readInt(minv, maxv, variablesName), int, true)
+}
+
+std::vector<int> InStream::readInts(int size, int indexBase) {
+    __testlib_readMany(readInts, readInt(), int, true)
+}
+
+std::vector<int> InStream::readIntegers(int size, int minv, int maxv, const std::string &variablesName, int indexBase) {
+    if (strict && !variablesName.empty())
+        validator.addVariable(variablesName);
+    __testlib_readMany(readIntegers, readInt(minv, maxv, variablesName), int, true)
+}
+
+std::vector<int> InStream::readIntegers(int size, int indexBase) {
+    __testlib_readMany(readIntegers, readInt(), int, true)
+}
+
+double InStream::readReal() {
+    if (!strict && seekEof())
+        quit(_unexpected_eof, "Unexpected end of file - double expected");
+
+    return stringToDouble(*this, readWord());
+}
+
+double InStream::readDouble() {
+    return readReal();
+}
+
+double InStream::readReal(double minv, double maxv, const std::string &variableName) {
+    double result = readReal();
+
+    if (result < minv || result > maxv) {
+        if (readManyIteration == NO_INDEX) {
+            if (variableName.empty())
+                quit(_wa, ("Double " + vtos(result) + " violates the range [" + vtos(minv) + ", " + vtos(maxv) +
+                           "]").c_str());
+            else
+                quit(_wa, ("Double parameter [name=" + std::string(variableName) + "] equals to " + vtos(result) +
+                           ", violates the range [" + vtos(minv) + ", " + vtos(maxv) + "]").c_str());
+        } else {
+            if (variableName.empty())
+                quit(_wa, ("Double element [index=" + vtos(readManyIteration) + "] equals to " + vtos(result) +
+                           ", violates the range [" + vtos(minv) + ", " + vtos(maxv) + "]").c_str());
+            else
+                quit(_wa,
+                     ("Double element " + std::string(variableName) + "[" + vtos(readManyIteration) + "] equals to " +
+                      vtos(result) + ", violates the range [" + vtos(minv) + ", " + vtos(maxv) + "]").c_str());
+        }
+    }
+
+    if (strict && !variableName.empty()) {
+        validator.addBoundsHit(variableName, ValidatorBoundsHit(
+                doubleDelta(minv, result) < ValidatorBoundsHit::EPS,
+                doubleDelta(maxv, result) < ValidatorBoundsHit::EPS
+        ));
+        validator.adjustConstantBounds(variableName, minv, maxv);
+        validator.addVariable(variableName);
+    }
+    
+    return result;
+}
+
+std::vector<double>
+InStream::readReals(int size, double minv, double maxv, const std::string &variablesName, int indexBase) {
+    if (strict && !variablesName.empty())
+        validator.addVariable(variablesName);
+    __testlib_readMany(readReals, readReal(minv, maxv, variablesName), double, true)
+}
+
+std::vector<double> InStream::readReals(int size, int indexBase) {
+    __testlib_readMany(readReals, readReal(), double, true)
+}
+
+double InStream::readDouble(double minv, double maxv, const std::string &variableName) {
+    return readReal(minv, maxv, variableName);
+}
+
+std::vector<double>
+InStream::readDoubles(int size, double minv, double maxv, const std::string &variablesName, int indexBase) {
+    if (strict && !variablesName.empty())
+        validator.addVariable(variablesName);
+    __testlib_readMany(readDoubles, readDouble(minv, maxv, variablesName), double, true)
+}
+
+std::vector<double> InStream::readDoubles(int size, int indexBase) {
+    __testlib_readMany(readDoubles, readDouble(), double, true)
+}
+
+double InStream::readStrictReal(double minv, double maxv,
+                                int minAfterPointDigitCount, int maxAfterPointDigitCount,
+                                const std::string &variableName) {
+    if (!strict && seekEof())
+        quit(_unexpected_eof, "Unexpected end of file - strict double expected");
+
+    double result = stringToStrictDouble(*this, readWord(), minAfterPointDigitCount, maxAfterPointDigitCount);
+
+    if (result < minv || result > maxv) {
+        if (readManyIteration == NO_INDEX) {
+            if (variableName.empty())
+                quit(_wa, ("Strict double " + vtos(result) + " violates the range [" + vtos(minv) + ", " + vtos(maxv) +
+                           "]").c_str());
+            else
+                quit(_wa,
+                     ("Strict double parameter [name=" + std::string(variableName) + "] equals to " + vtos(result) +
+                      ", violates the range [" + vtos(minv) + ", " + vtos(maxv) + "]").c_str());
+        } else {
+            if (variableName.empty())
+                quit(_wa, ("Strict double element [index=" + vtos(readManyIteration) + "] equals to " + vtos(result) +
+                           ", violates the range [" + vtos(minv) + ", " + vtos(maxv) + "]").c_str());
+            else
+                quit(_wa, ("Strict double element " + std::string(variableName) + "[" + vtos(readManyIteration) +
+                           "] equals to " + vtos(result) + ", violates the range [" + vtos(minv) + ", " + vtos(maxv) +
+                           "]").c_str());
+        }
+    }
+
+    if (strict && !variableName.empty()) {
+        validator.addBoundsHit(variableName, ValidatorBoundsHit(
+                doubleDelta(minv, result) < ValidatorBoundsHit::EPS,
+                doubleDelta(maxv, result) < ValidatorBoundsHit::EPS
+        ));
+        validator.adjustConstantBounds(variableName, minv, maxv);
+        validator.addVariable(variableName);
+    }
+
+    return result;
+}
+
+std::vector<double> InStream::readStrictReals(int size, double minv, double maxv,
+                                              int minAfterPointDigitCount, int maxAfterPointDigitCount,
+                                              const std::string &variablesName, int indexBase) {
+    if (strict && !variablesName.empty())
+        validator.addVariable(variablesName);
+    __testlib_readMany(readStrictReals,
+                       readStrictReal(minv, maxv, minAfterPointDigitCount, maxAfterPointDigitCount, variablesName),
+                       double, true)
+}
+
+double InStream::readStrictDouble(double minv, double maxv,
+                                  int minAfterPointDigitCount, int maxAfterPointDigitCount,
+                                  const std::string &variableName) {
+    return readStrictReal(minv, maxv,
+                          minAfterPointDigitCount, maxAfterPointDigitCount,
+                          variableName);
+}
+
+std::vector<double> InStream::readStrictDoubles(int size, double minv, double maxv,
+                                                int minAfterPointDigitCount, int maxAfterPointDigitCount,
+                                                const std::string &variablesName, int indexBase) {
+    if (strict && !variablesName.empty())
+        validator.addVariable(variablesName);
+    __testlib_readMany(readStrictDoubles,
+                       readStrictDouble(minv, maxv, minAfterPointDigitCount, maxAfterPointDigitCount, variablesName),
+                       double, true)
+}
+
+bool InStream::eof() {
+    if (!strict && NULL == reader)
+        return true;
+
+    return reader->eof();
+}
+
+bool InStream::seekEof() {
+    if (!strict && NULL == reader)
+        return true;
+    skipBlanks();
+    return eof();
+}
+
+bool InStream::eoln() {
+    if (!strict && NULL == reader)
+        return true;
+
+    int c = reader->nextChar();
+
+    if (!strict) {
+        if (c == EOFC)
+            return true;
+
+        if (c == CR) {
+            c = reader->nextChar();
+
+            if (c != LF) {
+                reader->unreadChar(c);
+                reader->unreadChar(CR);
+                return false;
+            } else
+                return true;
+        }
+
+        if (c == LF)
+            return true;
+
+        reader->unreadChar(c);
+        return false;
+    } else {
+        bool returnCr = false;
+
+#if (defined(ON_WINDOWS) && !defined(FOR_LINUX)) || defined(FOR_WINDOWS)
+        if (c != CR) {
+            reader->unreadChar(c);
+            return false;
+        } else {
+            if (!returnCr)
+                returnCr = true;
+            c = reader->nextChar();
+        }
+#endif
+        if (c != LF) {
+            reader->unreadChar(c);
+            if (returnCr)
+                reader->unreadChar(CR);
+            return false;
+        }
+
+        return true;
+    }
+}
+
+void InStream::readEoln() {
+    lastLine = reader->getLine();
+    if (!eoln())
+        quit(_pe, "Expected EOLN");
+}
+
+void InStream::readEof() {
+    lastLine = reader->getLine();
+    if (!eof())
+        quit(_pe, "Expected EOF");
+
+    if (TestlibFinalizeGuard::alive && this == &inf)
+        testlibFinalizeGuard.readEofCount++;
+}
+
+bool InStream::seekEoln() {
+    if (!strict && NULL == reader)
+        return true;
+
+    int cur;
+    do {
+        cur = reader->nextChar();
+    } while (cur == SPACE || cur == TAB);
+
+    reader->unreadChar(cur);
+    return eoln();
+}
+
+void InStream::nextLine() {
+    readLine();
+}
+
+void InStream::readStringTo(std::string &result) {
+    if (NULL == reader)
+        quit(_pe, "Expected line");
+
+    result.clear();
+
+    for (;;) {
+        int cur = reader->curChar();
+
+        if (cur == LF || cur == EOFC)
+            break;
+
+        if (cur == CR) {
+            cur = reader->nextChar();
+            if (reader->curChar() == LF) {
+                reader->unreadChar(cur);
+                break;
+            }
+        }
+
+        lastLine = reader->getLine();
+        result += char(reader->nextChar());
+    }
+
+    if (strict)
+        readEoln();
+    else
+        eoln();
+}
+
+std::string InStream::readString() {
+    readStringTo(_tmpReadToken);
+    return _tmpReadToken;
+}
+
+std::vector<std::string> InStream::readStrings(int size, int indexBase) {
+    __testlib_readMany(readStrings, readString(), std::string, false)
+}
+
+void InStream::readStringTo(std::string &result, const pattern &p, const std::string &variableName) {
+    readStringTo(result);
+    if (!p.matches(result)) {
+        if (readManyIteration == NO_INDEX) {
+            if (variableName.empty())
+                quit(_wa, ("Line \"" + __testlib_part(result) + "\" doesn't correspond to pattern \"" + p.src() +
+                           "\"").c_str());
+            else
+                quit(_wa, ("Line [name=" + variableName + "] equals to \"" + __testlib_part(result) +
+                           "\", doesn't correspond to pattern \"" + p.src() + "\"").c_str());
+        } else {
+            if (variableName.empty())
+                quit(_wa,
+                     ("Line element [index=" + vtos(readManyIteration) + "] equals to \"" + __testlib_part(result) +
+                      "\" doesn't correspond to pattern \"" + p.src() + "\"").c_str());
+            else
+                quit(_wa,
+                     ("Line element " + std::string(variableName) + "[" + vtos(readManyIteration) + "] equals to \"" +
+                      __testlib_part(result) + "\", doesn't correspond to pattern \"" + p.src() + "\"").c_str());
+        }
+    }
+    if (strict && !variableName.empty())
+        validator.addVariable(variableName);
+}
+
+void InStream::readStringTo(std::string &result, const std::string &ptrn, const std::string &variableName) {
+    readStringTo(result, pattern(ptrn), variableName);
+}
+
+std::string InStream::readString(const pattern &p, const std::string &variableName) {
+    readStringTo(_tmpReadToken, p, variableName);
+    return _tmpReadToken;
+}
+
+std::vector<std::string>
+InStream::readStrings(int size, const pattern &p, const std::string &variablesName, int indexBase) {
+    if (strict && !variablesName.empty())
+        validator.addVariable(variablesName);
+    __testlib_readMany(readStrings, readString(p, variablesName), std::string, false)
+}
+
+std::string InStream::readString(const std::string &ptrn, const std::string &variableName) {
+    readStringTo(_tmpReadToken, ptrn, variableName);
+    return _tmpReadToken;
+}
+
+std::vector<std::string>
+InStream::readStrings(int size, const std::string &ptrn, const std::string &variablesName, int indexBase) {
+    pattern p(ptrn);
+    if (strict && !variablesName.empty())
+        validator.addVariable(variablesName);
+    __testlib_readMany(readStrings, readString(p, variablesName), std::string, false)
+}
+
+void InStream::readLineTo(std::string &result) {
+    readStringTo(result);
+}
+
+std::string InStream::readLine() {
+    return readString();
+}
+
+std::vector<std::string> InStream::readLines(int size, int indexBase) {
+    __testlib_readMany(readLines, readString(), std::string, false)
+}
+
+void InStream::readLineTo(std::string &result, const pattern &p, const std::string &variableName) {
+    readStringTo(result, p, variableName);
+}
+
+void InStream::readLineTo(std::string &result, const std::string &ptrn, const std::string &variableName) {
+    readStringTo(result, ptrn, variableName);
+}
+
+std::string InStream::readLine(const pattern &p, const std::string &variableName) {
+    return readString(p, variableName);
+}
+
+std::vector<std::string>
+InStream::readLines(int size, const pattern &p, const std::string &variablesName, int indexBase) {
+    if (strict && !variablesName.empty())
+        validator.addVariable(variablesName);
+    __testlib_readMany(readLines, readString(p, variablesName), std::string, false)
+}
+
+std::string InStream::readLine(const std::string &ptrn, const std::string &variableName) {
+    return readString(ptrn, variableName);
+}
+
+std::vector<std::string>
+InStream::readLines(int size, const std::string &ptrn, const std::string &variablesName, int indexBase) {
+    pattern p(ptrn);
+    if (strict && !variablesName.empty())
+        validator.addVariable(variablesName);
+    __testlib_readMany(readLines, readString(p, variablesName), std::string, false)
+}
+
+#ifdef __GNUC__
+__attribute__ ((format (printf, 3, 4)))
+#endif
+void InStream::ensuref(bool cond, const char *format, ...) {
+    if (!cond) {
+        FMT_TO_RESULT(format, format, message);
+        this->__testlib_ensure(cond, message);
+    }
+}
+
+void InStream::__testlib_ensure(bool cond, std::string message) {
+    if (!cond)
+        this->quit(_wa, message.c_str());
+}
+
+void InStream::close() {
+    if (NULL != reader) {
+        reader->close();
+        delete reader;
+        reader = NULL;
+    }
+
+    opened = false;
+}
+
+NORETURN void quit(TResult result, const std::string &msg) {
+    ouf.quit(result, msg.c_str());
+}
+
+NORETURN void quit(TResult result, const char *msg) {
+    ouf.quit(result, msg);
+}
+
+double __testlib_preparePoints(double points_) {
+    volatile double points = points_;
+    if (__testlib_isNaN(points))
+        quit(_fail, "Parameter 'points' can't be nan");
+    if (__testlib_isInfinite(points))
+        quit(_fail, "Parameter 'points' can't be infinite");
+    if (points < -1E-8)
+        quit(_fail, "Parameter 'points' can't be negative");
+    if (points <= 0.0)
+        points = +0.0;
+    if (points > 1E6 + 1E-8)
+        quit(_fail, "Parameter 'points' can't be greater than 1E6");
+    if (points >= 1E6)
+        points = 1E6;
+    return points;
+}
+
+NORETURN void __testlib_quitp(double points, const char *message) {
+    __testlib_points = __testlib_preparePoints(points);
+    std::string stringPoints = removeDoubleTrailingZeroes(testlib_format_("%.10f", __testlib_points));
+
+    std::string quitMessage;
+    if (NULL == message || 0 == strlen(message))
+        quitMessage = stringPoints;
+    else
+        quitMessage = stringPoints + " " + message;
+
+    quit(_points, quitMessage.c_str());
+}
+
+NORETURN void __testlib_quitp(int points, const char *message) {
+    __testlib_points = __testlib_preparePoints(points);
+    std::string stringPoints = testlib_format_("%d", points);
+
+    std::string quitMessage;
+    if (NULL == message || 0 == strlen(message))
+        quitMessage = stringPoints;
+    else
+        quitMessage = stringPoints + " " + message;
+
+    quit(_points, quitMessage.c_str());
+}
+
+NORETURN void quitp(float points, const std::string &message = "") {
+    __testlib_quitp(double(points), message.c_str());
+}
+
+NORETURN void quitp(double points, const std::string &message = "") {
+    __testlib_quitp(points, message.c_str());
+}
+
+NORETURN void quitp(long double points, const std::string &message = "") {
+    __testlib_quitp(double(points), message.c_str());
+}
+
+NORETURN void quitp(int points, const std::string &message = "") {
+    __testlib_quitp(points, message.c_str());
+}
+
+NORETURN void quitpi(const std::string &points_info, const std::string &message = "") {
+    if (points_info.find(' ') != std::string::npos)
+        quit(_fail, "Parameter 'points_info' can't contain spaces");
+    if (message.empty())
+        quit(_points, ("points_info=" + points_info).c_str());
+    else
+        quit(_points, ("points_info=" + points_info + " " + message).c_str());
+}
+
+template<typename F>
+#ifdef __GNUC__
+__attribute__ ((format (printf, 2, 3)))
+#endif
+NORETURN void quitp(F points, const char *format, ...) {
+    FMT_TO_RESULT(format, format, message);
+    quitp(points, message);
+}
+
+#ifdef __GNUC__
+__attribute__ ((format (printf, 2, 3)))
+#endif
+NORETURN void quitf(TResult result, const char *format, ...) {
+    FMT_TO_RESULT(format, format, message);
+    quit(result, message);
+}
+
+#ifdef __GNUC__
+__attribute__ ((format (printf, 3, 4)))
+#endif
+void quitif(bool condition, TResult result, const char *format, ...) {
+    if (condition) {
+        FMT_TO_RESULT(format, format, message);
+        quit(result, message);
+    }
+}
+
+NORETURN void __testlib_help() {
+    InStream::textColor(InStream::LightCyan);
+    std::fprintf(stderr, "TESTLIB %s, https://github.com/MikeMirzayanov/testlib/ ", VERSION);
+    std::fprintf(stderr, "by Mike Mirzayanov, copyright(c) 2005-2020\n");
+    std::fprintf(stderr, "Checker name: \"%s\"\n", checkerName.c_str());
+    InStream::textColor(InStream::LightGray);
+
+    std::fprintf(stderr, "\n");
+    std::fprintf(stderr, "Latest features: \n");
+    for (size_t i = 0; i < sizeof(latestFeatures) / sizeof(char *); i++) {
+        std::fprintf(stderr, "*) %s\n", latestFeatures[i]);
+    }
+    std::fprintf(stderr, "\n");
+
+    std::fprintf(stderr, "Program must be run with the following arguments: \n");
+    std::fprintf(stderr, "    [--testset testset] [--group group] <input-file> <output-file> <answer-file> [<report-file> [<-appes>]]\n\n");
+
+    __testlib_exitCode = FAIL_EXIT_CODE;
+    std::exit(FAIL_EXIT_CODE);
+}
+
+static void __testlib_ensuresPreconditions() {
+    // testlib assumes: sizeof(int) = 4.
+    __TESTLIB_STATIC_ASSERT(sizeof(int) == 4);
+
+    // testlib assumes: INT_MAX == 2147483647.
+    __TESTLIB_STATIC_ASSERT(INT_MAX == 2147483647);
+
+    // testlib assumes: sizeof(long long) = 8.
+    __TESTLIB_STATIC_ASSERT(sizeof(long long) == 8);
+
+    // testlib assumes: sizeof(double) = 8.
+    __TESTLIB_STATIC_ASSERT(sizeof(double) == 8);
+
+    // testlib assumes: no -ffast-math.
+    if (!__testlib_isNaN(+__testlib_nan()))
+        quit(_fail, "Function __testlib_isNaN is not working correctly: possible reason is '-ffast-math'");
+    if (!__testlib_isNaN(-__testlib_nan()))
+        quit(_fail, "Function __testlib_isNaN is not working correctly: possible reason is '-ffast-math'");
+}
+
+std::string __testlib_testset;
+
+std::string getTestset() {
+    return __testlib_testset;
+}
+
+std::string __testlib_group;
+
+std::string getGroup() {
+    return __testlib_group;
+}
+
+static void __testlib_set_testset_and_group(int argc, char* argv[]) {
+    for (int i = 1; i < argc; i++) {
+        if (!strcmp("--testset", argv[i])) {
+            if (i + 1 < argc && strlen(argv[i + 1]) > 0)
+                __testlib_testset = argv[++i];
+            else
+                quit(_fail, std::string("Expected non-empty testset after --testset command line parameter"));
+        } else if (!strcmp("--group", argv[i])) {
+            if (i + 1 < argc)
+                __testlib_group = argv[++i];
+            else
+                quit(_fail, std::string("Expected group after --group command line parameter"));
+        }
+    }
+}
+
+void registerGen(int argc, char *argv[], int randomGeneratorVersion) {
+    if (randomGeneratorVersion < 0 || randomGeneratorVersion > 1)
+        quitf(_fail, "Random generator version is expected to be 0 or 1.");
+    random_t::version = randomGeneratorVersion;
+
+    __testlib_ensuresPreconditions();
+    TestlibFinalizeGuard::registered = true;
+
+    testlibMode = _generator;
+    __testlib_set_binary(stdin);
+    rnd.setSeed(argc, argv);
+
+#if __cplusplus > 199711L || defined(_MSC_VER)
+    prepareOpts(argc, argv);
+#endif
+}
+
+#ifdef USE_RND_AS_BEFORE_087
+void registerGen(int argc, char* argv[])
+{
+    registerGen(argc, argv, 0);
+}
+#else
+#ifdef __GNUC__
+#if (__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ > 4))
+__attribute__ ((deprecated("Use registerGen(argc, argv, 0) or registerGen(argc, argv, 1)."
+" The third parameter stands for the random generator version."
+" If you are trying to compile old generator use macro -DUSE_RND_AS_BEFORE_087 or registerGen(argc, argv, 0)."
+" Version 1 has been released on Spring, 2013. Use it to write new generators.")))
+#else
+__attribute__ ((deprecated))
+#endif
+#endif
+#ifdef _MSC_VER
+__declspec(deprecated("Use registerGen(argc, argv, 0) or registerGen(argc, argv, 1)."
+        " The third parameter stands for the random generator version."
+        " If you are trying to compile old generator use macro -DUSE_RND_AS_BEFORE_087 or registerGen(argc, argv, 0)."
+        " Version 1 has been released on Spring, 2013. Use it to write new generators."))
+#endif
+void registerGen(int argc, char *argv[]) {
+    std::fprintf(stderr, "Use registerGen(argc, argv, 0) or registerGen(argc, argv, 1)."
+                         " The third parameter stands for the random generator version."
+                         " If you are trying to compile old generator use macro -DUSE_RND_AS_BEFORE_087 or registerGen(argc, argv, 0)."
+                         " Version 1 has been released on Spring, 2013. Use it to write new generators.\n\n");
+    registerGen(argc, argv, 0);
+}
+#endif
+
+void setAppesModeEncoding(std::string appesModeEncoding) {
+    static const char* const ENCODINGS[] = {"ascii", "utf-7", "utf-8", "utf-16", "utf-16le", "utf-16be", "utf-32", "utf-32le", "utf-32be", "iso-8859-1", 
+"iso-8859-2", "iso-8859-3", "iso-8859-4", "iso-8859-5", "iso-8859-6", "iso-8859-7", "iso-8859-8", "iso-8859-9", "iso-8859-10", "iso-8859-11", 
+"iso-8859-13", "iso-8859-14", "iso-8859-15", "iso-8859-16", "windows-1250", "windows-1251", "windows-1252", "windows-1253", "windows-1254", "windows-1255", 
+"windows-1256", "windows-1257", "windows-1258", "gb2312", "gbk", "gb18030", "big5", "shift-jis", "euc-jp", "euc-kr", 
+"euc-cn", "euc-tw", "koi8-r", "koi8-u", "tis-620", "ibm437", "ibm850", "ibm852", "ibm855", "ibm857", 
+"ibm860", "ibm861", "ibm862", "ibm863", "ibm865", "ibm866", "ibm869", "macroman", "maccentraleurope", "maciceland", 
+"maccroatian", "macromania", "maccyrillic", "macukraine", "macgreek", "macturkish", "machebrew", "macarabic", "macthai", "hz-gb-2312", 
+"iso-2022-jp", "iso-2022-kr", "iso-2022-cn", "armscii-8", "tscii", "iscii", "viscii", "geostd8", "cp949", "cp874", 
+"cp1006", "cp775", "cp858", "cp737", "cp853", "cp856", "cp922", "cp1046", "cp1125", "cp1131", 
+"ptcp154", "koi8-t", "koi8-ru", "mulelao-1", "cp1133", "iso-ir-166", "tcvn", "iso-ir-14", "iso-ir-87", "iso-ir-159"};
+    
+    appesModeEncoding = lowerCase(appesModeEncoding);
+    bool valid = false;
+    for (size_t i = 0; i < sizeof(ENCODINGS) / sizeof(ENCODINGS[0]); i++)
+        if (appesModeEncoding == ENCODINGS[i]) {
+            valid = true;
+            break;
+        }
+    if (!valid)
+        quit(_fail, "Unexpected encoding for setAppesModeEncoding(encoding)");
+    ::appesModeEncoding = appesModeEncoding;
+}
+
+void registerInteraction(int argc, char *argv[]) {
+    __testlib_ensuresPreconditions();
+    __testlib_set_testset_and_group(argc, argv);
+    TestlibFinalizeGuard::registered = true;
+
+    testlibMode = _interactor;
+    __testlib_set_binary(stdin);
+
+    if (argc > 1 && !strcmp("--help", argv[1]))
+        __testlib_help();
+
+    if (argc < 3 || argc > 6) {
+        quit(_fail, std::string("Program must be run with the following arguments: ") +
+                    std::string("<input-file> <output-file> [<answer-file> [<report-file> [<-appes>]]]") +
+                    "\nUse \"--help\" to get help information");
+    }
+
+    if (argc <= 4) {
+        resultName = "";
+        appesMode = false;
+    }
+
+#ifndef EJUDGE
+    if (argc == 5) {
+        resultName = argv[4];
+        appesMode = false;
+    }
+
+    if (argc == 6) {
+        if (strcmp("-APPES", argv[5]) && strcmp("-appes", argv[5])) {
+            quit(_fail, std::string("Program must be run with the following arguments: ") +
+                        "<input-file> <output-file> <answer-file> [<report-file> [<-appes>]]");
+        } else {
+            resultName = argv[4];
+            appesMode = true;
+        }
+    }
+#endif
+
+    inf.init(argv[1], _input);
+
+    tout.open(argv[2], std::ios_base::out);
+    if (tout.fail() || !tout.is_open())
+        quit(_fail, std::string("Can not write to the test-output-file '") + argv[2] + std::string("'"));
+
+    ouf.init(stdin, _output);
+
+    if (argc >= 4)
+        ans.init(argv[3], _answer);
+    else
+        ans.name = "unopened answer stream";
+}
+
+void registerValidation() {
+    __testlib_ensuresPreconditions();
+    TestlibFinalizeGuard::registered = true;
+
+    testlibMode = _validator;
+
+    __testlib_set_binary(stdin);
+    __testlib_set_binary(stdout);
+    __testlib_set_binary(stderr);
+
+    inf.init(stdin, _input);
+    inf.strict = true;
+}
+
+void registerValidation(int argc, char *argv[]) {
+    registerValidation();
+    __testlib_set_testset_and_group(argc, argv);
+
+    validator.initialize();
+    TestlibFinalizeGuard::registered = true;
+
+    std::string comment = "Validator must be run with the following arguments:"
+                            " [--testset testset]"
+                            " [--group group]"
+                            " [--testOverviewLogFileName fileName]"
+                            " [--testMarkupFileName fileName]"
+                            " [--testCase testCase]"
+                            " [--testCaseFileName fileName]"
+                            ;
+
+    for (int i = 1; i < argc; i++) {
+        if (!strcmp("--testset", argv[i])) {
+            if (i + 1 < argc && strlen(argv[i + 1]) > 0)
+                validator.setTestset(argv[++i]);
+            else
+                quit(_fail, comment);
+        }
+        if (!strcmp("--group", argv[i])) {
+            if (i + 1 < argc)
+                validator.setGroup(argv[++i]);
+            else
+                quit(_fail, comment);
+        }
+        if (!strcmp("--testOverviewLogFileName", argv[i])) {
+            if (i + 1 < argc)
+                validator.setTestOverviewLogFileName(argv[++i]);
+            else
+                quit(_fail, comment);
+        }
+        if (!strcmp("--testMarkupFileName", argv[i])) {
+            if (i + 1 < argc)
+                validator.setTestMarkupFileName(argv[++i]);
+            else
+                quit(_fail, comment);
+        }
+        if (!strcmp("--testCase", argv[i])) {
+            if (i + 1 < argc) {
+                long long testCase = stringToLongLong(inf, argv[++i]);
+                if (testCase < 1 || testCase >= __TESTLIB_MAX_TEST_CASE)
+                    quit(_fail, testlib_format_("Argument testCase should be between 1 and %d, but ", __TESTLIB_MAX_TEST_CASE)
+                        + toString(testCase) + " found");
+                validator.setTestCase(int(testCase));
+            } else
+                quit(_fail, comment);
+        }
+        if (!strcmp("--testCaseFileName", argv[i])) {
+            if (i + 1 < argc) {
+                validator.setTestCaseFileName(argv[++i]);
+            } else
+                quit(_fail, comment);
+        }
+    }
+}
+
+void addFeature(const std::string &feature) {
+    if (testlibMode != _validator)
+        quit(_fail, "Features are supported in validators only.");
+    validator.addFeature(feature);
+}
+
+void feature(const std::string &feature) {
+    if (testlibMode != _validator)
+        quit(_fail, "Features are supported in validators only.");
+    validator.feature(feature);
+}
+
+class Checker {
+private:
+    bool _initialized;
+    std::string _testset;
+    std::string _group;
+
+public:
+    Checker() : _initialized(false), _testset("tests"), _group() {
+    }
+
+    void initialize() {
+        _initialized = true;
+    }
+
+    std::string testset() const {
+        if (!_initialized)
+            __testlib_fail("Checker should be initialized with registerTestlibCmd(argc, argv) instead of registerTestlibCmd() to support checker.testset()");
+        return _testset;
+    }
+
+    std::string group() const {
+        if (!_initialized)
+            __testlib_fail("Checker should be initialized with registerTestlibCmd(argc, argv) instead of registerTestlibCmd() to support checker.group()");
+        return _group;
+    }
+
+    void setTestset(const char *const testset) {
+        _testset = testset;
+    }
+
+    void setGroup(const char *const group) {
+        _group = group;
+    }
+} checker;
+
+void registerTestlibCmd(int argc, char *argv[]) {
+    __testlib_ensuresPreconditions();
+    __testlib_set_testset_and_group(argc, argv);
+    TestlibFinalizeGuard::registered = true;
+
+    testlibMode = _checker;
+    __testlib_set_binary(stdin);
+
+    std::vector<std::string> args(1, argv[0]);
+    checker.initialize();
+
+    for (int i = 1; i < argc; i++) {
+        if (!strcmp("--testset", argv[i])) {
+            if (i + 1 < argc && strlen(argv[i + 1]) > 0)
+                checker.setTestset(argv[++i]);
+            else
+                quit(_fail, std::string("Expected testset after --testset command line parameter"));
+        } else if (!strcmp("--group", argv[i])) {
+            if (i + 1 < argc)
+                checker.setGroup(argv[++i]);
+            else
+                quit(_fail, std::string("Expected group after --group command line parameter"));
+        } else
+            args.push_back(argv[i]);
+    }
+
+    argc = int(args.size());
+    if (argc > 1 && "--help" == args[1])
+        __testlib_help();
+
+    if (argc < 4 || argc > 6) {
+        quit(_fail, std::string("Program must be run with the following arguments: ") +
+                    std::string("[--testset testset] [--group group] <input-file> <output-file> <answer-file> [<report-file> [<-appes>]]") +
+                    "\nUse \"--help\" to get help information");
+    }
+
+    if (argc == 4) {
+        resultName = "";
+        appesMode = false;
+    }
+
+#ifndef EJUDGE
+    if (argc == 5) {
+        resultName = args[4];
+        appesMode = false;
+    }
+
+    if (argc == 6) {
+        if ("-APPES" != args[5] && "-appes" != args[5]) {
+            quit(_fail, std::string("Program must be run with the following arguments: ") +
+                        "<input-file> <output-file> <answer-file> [<report-file> [<-appes>]]");
+        } else {
+            resultName = args[4];
+            appesMode = true;
+        }
+    }
+#endif
+
+    inf.init(args[1], _input);
+    ouf.init(args[2], _output);
+    ouf.skipBom();
+    ans.init(args[3], _answer);
+}
+
+void registerTestlib(int argc, ...) {
+    if (argc < 3 || argc > 5)
+        quit(_fail, std::string("Program must be run with the following arguments: ") +
+                    "<input-file> <output-file> <answer-file> [<report-file> [<-appes>]]");
+
+    char **argv = new char *[argc + 1];
+
+    va_list ap;
+    va_start(ap, argc);
+    argv[0] = NULL;
+    for (int i = 0; i < argc; i++) {
+        argv[i + 1] = va_arg(ap, char*);
+    }
+    va_end(ap);
+
+    registerTestlibCmd(argc + 1, argv);
+    delete[] argv;
+}
+
+static inline void __testlib_ensure(bool cond, const std::string &msg) {
+    if (!cond)
+        quit(_fail, msg.c_str());
+}
+
+#ifdef __GNUC__
+__attribute__((unused))
+#endif
+static inline void __testlib_ensure(bool cond, const char *msg) {
+    if (!cond)
+        quit(_fail, msg);
+}
+
+#define ensure(cond) __testlib_ensure((cond), "Condition failed: \"" #cond "\"")
+#define STRINGIZE_DETAIL(x) (#x)
+#define STRINGIZE(x) STRINGIZE_DETAIL((x))
+#define ensure_ext(cond) __testlib_ensure((cond), "Line " STRINGIZE(__LINE__) ": Condition failed: \"" #cond "\"")
+
+#ifdef __GNUC__
+__attribute__ ((format (printf, 2, 3)))
+#endif
+inline void ensuref(bool cond, const char *format, ...) {
+    if (!cond) {
+        FMT_TO_RESULT(format, format, message);
+        __testlib_ensure(cond, message);
+    }
+}
+
+NORETURN static void __testlib_fail(const std::string &message) {
+    quitf(_fail, "%s", message.c_str());
+}
+
+#ifdef __GNUC__
+__attribute__ ((format (printf, 1, 2)))
+#endif
+void setName(const char *format, ...) {
+    FMT_TO_RESULT(format, format, name);
+    checkerName = name;
+}
+
+/*
+ * Do not use random_shuffle, because it will produce different result
+ * for different C++ compilers.
+ *
+ * This implementation uses testlib random_t to produce random numbers, so
+ * it is stable.
+ */
+template<typename _RandomAccessIter>
+void shuffle(_RandomAccessIter __first, _RandomAccessIter __last) {
+    if (__first == __last) return;
+    for (_RandomAccessIter __i = __first + 1; __i != __last; ++__i)
+        std::iter_swap(__i, __first + rnd.next(int(__i - __first) + 1));
+}
+
+
+template<typename _RandomAccessIter>
+#if defined(__GNUC__) && !defined(__clang__)
+__attribute__ ((error("Don't use random_shuffle(), use shuffle() instead")))
+#endif
+void random_shuffle(_RandomAccessIter, _RandomAccessIter) {
+    quitf(_fail, "Don't use random_shuffle(), use shuffle() instead");
+}
+
+#ifdef __GLIBC__
+#  define RAND_THROW_STATEMENT throw()
+#else
+#  define RAND_THROW_STATEMENT
+#endif
+
+#if defined(__GNUC__) && !defined(__clang__)
+
+__attribute__ ((error("Don't use rand(), use rnd.next() instead")))
+#endif
+#ifdef _MSC_VER
+#   pragma warning( disable : 4273 )
+#endif
+int rand() RAND_THROW_STATEMENT
+{
+    quitf(_fail, "Don't use rand(), use rnd.next() instead");
+
+    /* This line never runs. */
+    //throw "Don't use rand(), use rnd.next() instead";
+}
+
+#if defined(__GNUC__) && !defined(__clang__)
+
+__attribute__ ((error("Don't use srand(), you should use "
+"'registerGen(argc, argv, 1);' to initialize generator seed "
+"by hash code of the command line params. The third parameter "
+"is randomGeneratorVersion (currently the latest is 1).")))
+#endif
+#ifdef _MSC_VER
+#   pragma warning( disable : 4273 )
+#endif
+void srand(unsigned int seed) RAND_THROW_STATEMENT
+{
+    quitf(_fail, "Don't use srand(), you should use "
+                 "'registerGen(argc, argv, 1);' to initialize generator seed "
+                 "by hash code of the command line params. The third parameter "
+                 "is randomGeneratorVersion (currently the latest is 1) [ignored seed=%u].", seed);
+}
+
+void startTest(int test) {
+    const std::string testFileName = vtos(test);
+    if (NULL == testlib_freopen_(testFileName.c_str(), "wt", stdout))
+        __testlib_fail("Unable to write file '" + testFileName + "'");
+}
+
+#ifdef __GNUC__
+__attribute__((const))
+#endif
+inline std::string compress(const std::string &s) {
+    return __testlib_part(s);
+}
+
+#ifdef __GNUC__
+__attribute__((const))
+#endif
+inline std::string englishEnding(int x) {
+    x %= 100;
+    if (x / 10 == 1)
+        return "th";
+    if (x % 10 == 1)
+        return "st";
+    if (x % 10 == 2)
+        return "nd";
+    if (x % 10 == 3)
+        return "rd";
+    return "th";
+}
+
+template<typename _ForwardIterator, typename _Separator>
+#ifdef __GNUC__
+__attribute__((const))
+#endif
+std::string join(_ForwardIterator first, _ForwardIterator last, _Separator separator) {
+    std::stringstream ss;
+    bool repeated = false;
+    for (_ForwardIterator i = first; i != last; i++) {
+        if (repeated)
+            ss << separator;
+        else
+            repeated = true;
+        ss << *i;
+    }
+    return ss.str();
+}
+
+template<typename _ForwardIterator>
+#ifdef __GNUC__
+__attribute__((const))
+#endif
+std::string join(_ForwardIterator first, _ForwardIterator last) {
+    return join(first, last, ' ');
+}
+
+template<typename _Collection, typename _Separator>
+#ifdef __GNUC__
+__attribute__((const))
+#endif
+std::string join(const _Collection &collection, _Separator separator) {
+    return join(collection.begin(), collection.end(), separator);
+}
+
+template<typename _Collection>
+#ifdef __GNUC__
+__attribute__((const))
+#endif
+std::string join(const _Collection &collection) {
+    return join(collection, ' ');
+}
+
+/**
+ * Splits string s by character separator returning exactly k+1 items,
+ * where k is the number of separator occurrences.
+ */
+#ifdef __GNUC__
+__attribute__((const))
+#endif
+std::vector<std::string> split(const std::string &s, char separator) {
+    std::vector<std::string> result;
+    std::string item;
+    for (size_t i = 0; i < s.length(); i++)
+        if (s[i] == separator) {
+            result.push_back(item);
+            item = "";
+        } else
+            item += s[i];
+    result.push_back(item);
+    return result;
+}
+
+/**
+ * Splits string s by character separators returning exactly k+1 items,
+ * where k is the number of separator occurrences.
+ */
+#ifdef __GNUC__
+__attribute__((const))
+#endif
+std::vector<std::string> split(const std::string &s, const std::string &separators) {
+    if (separators.empty())
+        return std::vector<std::string>(1, s);
+
+    std::vector<bool> isSeparator(256);
+    for (size_t i = 0; i < separators.size(); i++)
+        isSeparator[(unsigned char) (separators[i])] = true;
+
+    std::vector<std::string> result;
+    std::string item;
+    for (size_t i = 0; i < s.length(); i++)
+        if (isSeparator[(unsigned char) (s[i])]) {
+            result.push_back(item);
+            item = "";
+        } else
+            item += s[i];
+    result.push_back(item);
+    return result;
+}
+
+/**
+ * Splits string s by character separator returning non-empty items.
+ */
+#ifdef __GNUC__
+__attribute__((const))
+#endif
+std::vector<std::string> tokenize(const std::string &s, char separator) {
+    std::vector<std::string> result;
+    std::string item;
+    for (size_t i = 0; i < s.length(); i++)
+        if (s[i] == separator) {
+            if (!item.empty())
+                result.push_back(item);
+            item = "";
+        } else
+            item += s[i];
+    if (!item.empty())
+        result.push_back(item);
+    return result;
+}
+
+/**
+ * Splits string s by character separators returning non-empty items.
+ */
+#ifdef __GNUC__
+__attribute__((const))
+#endif
+std::vector<std::string> tokenize(const std::string &s, const std::string &separators) {
+    if (separators.empty())
+        return std::vector<std::string>(1, s);
+
+    std::vector<bool> isSeparator(256);
+    for (size_t i = 0; i < separators.size(); i++)
+        isSeparator[(unsigned char) (separators[i])] = true;
+
+    std::vector<std::string> result;
+    std::string item;
+    for (size_t i = 0; i < s.length(); i++)
+        if (isSeparator[(unsigned char) (s[i])]) {
+            if (!item.empty())
+                result.push_back(item);
+            item = "";
+        } else
+            item += s[i];
+
+    if (!item.empty())
+        result.push_back(item);
+
+    return result;
+}
+
+NORETURN void __testlib_expectedButFound(TResult result, std::string expected, std::string found, const char *prepend) {
+    std::string message;
+    if (strlen(prepend) != 0)
+        message = testlib_format_("%s: expected '%s', but found '%s'",
+                         compress(prepend).c_str(), compress(expected).c_str(), compress(found).c_str());
+    else
+        message = testlib_format_("expected '%s', but found '%s'",
+                         compress(expected).c_str(), compress(found).c_str());
+    quit(result, message);
+}
+
+NORETURN void __testlib_expectedButFound(TResult result, double expected, double found, const char *prepend) {
+    std::string expectedString = removeDoubleTrailingZeroes(testlib_format_("%.12f", expected));
+    std::string foundString = removeDoubleTrailingZeroes(testlib_format_("%.12f", found));
+    __testlib_expectedButFound(result, expectedString, foundString, prepend);
+}
+
+template<typename T>
+#ifdef __GNUC__
+__attribute__ ((format (printf, 4, 5)))
+#endif
+NORETURN void expectedButFound(TResult result, T expected, T found, const char *prependFormat = "", ...) {
+    FMT_TO_RESULT(prependFormat, prependFormat, prepend);
+    std::string expectedString = vtos(expected);
+    std::string foundString = vtos(found);
+    __testlib_expectedButFound(result, expectedString, foundString, prepend.c_str());
+}
+
+template<>
+#ifdef __GNUC__
+__attribute__ ((format (printf, 4, 5)))
+#endif
+NORETURN void
+expectedButFound<std::string>(TResult result, std::string expected, std::string found, const char *prependFormat, ...) {
+    FMT_TO_RESULT(prependFormat, prependFormat, prepend);
+    __testlib_expectedButFound(result, expected, found, prepend.c_str());
+}
+
+template<>
+#ifdef __GNUC__
+__attribute__ ((format (printf, 4, 5)))
+#endif
+NORETURN void expectedButFound<double>(TResult result, double expected, double found, const char *prependFormat, ...) {
+    FMT_TO_RESULT(prependFormat, prependFormat, prepend);
+    std::string expectedString = removeDoubleTrailingZeroes(testlib_format_("%.12f", expected));
+    std::string foundString = removeDoubleTrailingZeroes(testlib_format_("%.12f", found));
+    __testlib_expectedButFound(result, expectedString, foundString, prepend.c_str());
+}
+
+template<>
+#ifdef __GNUC__
+__attribute__ ((format (printf, 4, 5)))
+#endif
+NORETURN void
+expectedButFound<const char *>(TResult result, const char *expected, const char *found, const char *prependFormat,
+                               ...) {
+    FMT_TO_RESULT(prependFormat, prependFormat, prepend);
+    __testlib_expectedButFound(result, std::string(expected), std::string(found), prepend.c_str());
+}
+
+template<>
+#ifdef __GNUC__
+__attribute__ ((format (printf, 4, 5)))
+#endif
+NORETURN void expectedButFound<float>(TResult result, float expected, float found, const char *prependFormat, ...) {
+    FMT_TO_RESULT(prependFormat, prependFormat, prepend);
+    __testlib_expectedButFound(result, double(expected), double(found), prepend.c_str());
+}
+
+template<>
+#ifdef __GNUC__
+__attribute__ ((format (printf, 4, 5)))
+#endif
+NORETURN void
+expectedButFound<long double>(TResult result, long double expected, long double found, const char *prependFormat, ...) {
+    FMT_TO_RESULT(prependFormat, prependFormat, prepend);
+    __testlib_expectedButFound(result, double(expected), double(found), prepend.c_str());
+}
+
+#if __cplusplus > 199711L || defined(_MSC_VER)
+template<typename T>
+struct is_iterable {
+    template<typename U>
+    static char test(typename U::iterator *x);
+
+    template<typename U>
+    static long test(U *x);
+
+    static const bool value = sizeof(test<T>(0)) == 1;
+};
+
+template<bool B, class T = void>
+struct __testlib_enable_if {
+};
+
+template<class T>
+struct __testlib_enable_if<true, T> {
+    typedef T type;
+};
+
+template<typename T>
+typename __testlib_enable_if<!is_iterable<T>::value, void>::type __testlib_print_one(const T &t) {
+    std::cout << t;
+}
+
+template<typename T>
+typename __testlib_enable_if<is_iterable<T>::value, void>::type __testlib_print_one(const T &t) {
+    bool first = true;
+    for (typename T::const_iterator i = t.begin(); i != t.end(); i++) {
+        if (first)
+            first = false;
+        else
+            std::cout << " ";
+        std::cout << *i;
+    }
+}
+
+template<>
+typename __testlib_enable_if<is_iterable<std::string>::value, void>::type
+__testlib_print_one<std::string>(const std::string &t) {
+    std::cout << t;
+}
+
+template<typename A, typename B>
+void __println_range(A begin, B end) {
+    bool first = true;
+    for (B i = B(begin); i != end; i++) {
+        if (first)
+            first = false;
+        else
+            std::cout << " ";
+        __testlib_print_one(*i);
+    }
+    std::cout << std::endl;
+}
+
+template<class T, class Enable = void>
+struct is_iterator {
+    static T makeT();
+
+    typedef void *twoptrs[2];
+
+    static twoptrs &test(...);
+
+    template<class R>
+    static typename R::iterator_category *test(R);
+
+    template<class R>
+    static void *test(R *);
+
+    static const bool value = sizeof(test(makeT())) == sizeof(void *);
+};
+
+template<class T>
+struct is_iterator<T, typename __testlib_enable_if<std::is_array<T>::value>::type> {
+    static const bool value = false;
+};
+
+template<typename A, typename B>
+typename __testlib_enable_if<!is_iterator<B>::value, void>::type println(const A &a, const B &b) {
+    __testlib_print_one(a);
+    std::cout << " ";
+    __testlib_print_one(b);
+    std::cout << std::endl;
+}
+
+template<typename A, typename B>
+typename __testlib_enable_if<is_iterator<B>::value, void>::type println(const A &a, const B &b) {
+    __println_range(a, b);
+}
+
+template<typename A>
+void println(const A *a, const A *b) {
+    __println_range(a, b);
+}
+
+template<>
+void println<char>(const char *a, const char *b) {
+    __testlib_print_one(a);
+    std::cout << " ";
+    __testlib_print_one(b);
+    std::cout << std::endl;
+}
+
+template<typename T>
+void println(const T &x) {
+    __testlib_print_one(x);
+    std::cout << std::endl;
+}
+
+template<typename A, typename B, typename C>
+void println(const A &a, const B &b, const C &c) {
+    __testlib_print_one(a);
+    std::cout << " ";
+    __testlib_print_one(b);
+    std::cout << " ";
+    __testlib_print_one(c);
+    std::cout << std::endl;
+}
+
+template<typename A, typename B, typename C, typename D>
+void println(const A &a, const B &b, const C &c, const D &d) {
+    __testlib_print_one(a);
+    std::cout << " ";
+    __testlib_print_one(b);
+    std::cout << " ";
+    __testlib_print_one(c);
+    std::cout << " ";
+    __testlib_print_one(d);
+    std::cout << std::endl;
+}
+
+template<typename A, typename B, typename C, typename D, typename E>
+void println(const A &a, const B &b, const C &c, const D &d, const E &e) {
+    __testlib_print_one(a);
+    std::cout << " ";
+    __testlib_print_one(b);
+    std::cout << " ";
+    __testlib_print_one(c);
+    std::cout << " ";
+    __testlib_print_one(d);
+    std::cout << " ";
+    __testlib_print_one(e);
+    std::cout << std::endl;
+}
+
+template<typename A, typename B, typename C, typename D, typename E, typename F>
+void println(const A &a, const B &b, const C &c, const D &d, const E &e, const F &f) {
+    __testlib_print_one(a);
+    std::cout << " ";
+    __testlib_print_one(b);
+    std::cout << " ";
+    __testlib_print_one(c);
+    std::cout << " ";
+    __testlib_print_one(d);
+    std::cout << " ";
+    __testlib_print_one(e);
+    std::cout << " ";
+    __testlib_print_one(f);
+    std::cout << std::endl;
+}
+
+template<typename A, typename B, typename C, typename D, typename E, typename F, typename G>
+void println(const A &a, const B &b, const C &c, const D &d, const E &e, const F &f, const G &g) {
+    __testlib_print_one(a);
+    std::cout << " ";
+    __testlib_print_one(b);
+    std::cout << " ";
+    __testlib_print_one(c);
+    std::cout << " ";
+    __testlib_print_one(d);
+    std::cout << " ";
+    __testlib_print_one(e);
+    std::cout << " ";
+    __testlib_print_one(f);
+    std::cout << " ";
+    __testlib_print_one(g);
+    std::cout << std::endl;
+}
+
+/* opts */
+
+/**
+ * A struct for a singular testlib opt, containing the raw string value,
+ * and a boolean value for marking whether the opt is used.
+ */
+struct TestlibOpt {
+    std::string value;
+    bool used;
+
+    TestlibOpt() : value(), used(false) {}
+};
+
+/**
+ * Get the type of opt based on the number of `-` at the beginning and the
+ * _validity_ of the key name.
+ * 
+ * A valid key name must start with an alphabetical character.
+ * 
+ * Returns: 1 if s has one `-` at the beginning, that is, "-keyName".
+ *          2 if s has two `-` at the beginning, that is, "--keyName".
+ *          0 otherwise. That is, if s has no `-` at the beginning, or has more
+ *          than 2 at the beginning ("---keyName", "----keyName", ...), or the
+ *          keyName is invalid (the first character is not an alphabetical
+ *          character).
+ */
+size_t getOptType(char *s) {
+    if (!s || strlen(s) <= 1)
+        return 0;
+
+    if (s[0] == '-') {
+        if (isalpha(s[1]))
+            return 1;
+        else if (s[1] == '-')
+            return isalpha(s[2]) ? 2 : 0;
+    }
+
+    return 0;
+}
+
+/**
+ * Parse the opt at a given index, and put it into the opts maps.
+ * 
+ * An opt can has the following form:
+ * 1) -keyName=value or --keyName=value     (ex. -n=10 --test-count=20)
+ * 2) -keyName value or --keyName value     (ex. -n 10 --test-count 20)
+ * 3) -kNumval       or --kNumval           (ex. -n10  --t20)
+ * 4) -boolProperty  or --boolProperty      (ex. -sorted --tree-only)
+ * 
+ * Only the second form consumes 2 arguments. The other consumes only 1
+ * argument.
+ * 
+ * In the third form, the key is a single character, and after the key is the
+ * value. The value _should_ be a number.
+ * 
+ * In the forth form, the value is true.
+ * 
+ * Params:
+ * - argc and argv: the number of command line arguments and the command line
+ *   arguments themselves.
+ * - index: the starting index of the opts.
+ * - opts: the map containing the resulting opt.
+ *  
+ * Returns: the number of consumed arguments to parse the opt.
+ *          0 if there is no arguments to parse.
+ * 
+ * Algorithm details:
+ * TODO. Please refer to the implementation to see how the code handles the 3rd and 4th forms separately.
+ */
+size_t parseOpt(size_t argc, char *argv[], size_t index, std::map<std::string, TestlibOpt> &opts) {
+    if (index >= argc)
+        return 0;
+
+    size_t type = getOptType(argv[index]), inc = 1;
+    if (type > 0) {
+        std::string key(argv[index] + type), val;
+        size_t sep = key.find('=');
+        if (sep != std::string::npos) {
+            val = key.substr(sep + 1);
+            key = key.substr(0, sep);
+        } else {
+            if (index + 1 < argc && getOptType(argv[index + 1]) == 0) {
+                val = argv[index + 1];
+                inc = 2;
+            } else {
+                if (key.length() > 1 && isdigit(key[1])) {
+                    val = key.substr(1);
+                    key = key.substr(0, 1);
+                } else {
+                    val = "true";
+                }
+            }
+        }
+        opts[key].value = val;
+    } else {
+        return inc;
+    }
+
+    return inc;
+}
+
+/**
+ * Global list containing all the arguments in the order given in the command line.
+ */
+std::vector<std::string> __testlib_argv;
+
+/**
+ * Global dictionary containing all the parsed opts.
+ */
+std::map<std::string, TestlibOpt> __testlib_opts;
+
+/**
+ * Whether automatic no unused opts ensurement should be done. This flag will
+ * be turned on when `has_opt` or `opt(key, default_value)` is called.
+ * 
+ * The automatic ensurement can be suppressed when
+ * __testlib_ensureNoUnusedOptsSuppressed is true.
+ */
+bool __testlib_ensureNoUnusedOptsFlag = false;
+
+/**
+ * Suppress no unused opts automatic ensurement. Can be set to true with
+ * `suppressEnsureNoUnusedOpts()`.
+ */
+bool __testlib_ensureNoUnusedOptsSuppressed = false;
+
+/**
+ * Parse command line arguments into opts.
+ * The results are stored into __testlib_argv and __testlib_opts.
+ */
+void prepareOpts(int argc, char *argv[]) {
+    if (argc <= 0)
+        __testlib_fail("Opts: expected argc>=0 but found " + toString(argc));
+    size_t n = static_cast<size_t>(argc); // NOLINT(hicpp-use-auto,modernize-use-auto)
+    __testlib_opts = std::map<std::string, TestlibOpt>();
+    for (size_t index = 1; index < n; index += parseOpt(n, argv, index, __testlib_opts));
+    __testlib_argv = std::vector<std::string>(n);
+    for (size_t index = 0; index < n; index++)
+        __testlib_argv[index] = argv[index];
+}
+
+/**
+ * An utility function to get the argument with a given index. This function
+ * also print a readable message when no arguments are found.
+ */
+std::string __testlib_indexToArgv(int index) {
+    if (index < 0 || index >= int(__testlib_argv.size()))
+        __testlib_fail("Opts: index '" + toString(index) + "' is out of range [0,"
+            + toString(__testlib_argv.size()) + ")");
+    return __testlib_argv[size_t(index)];
+}
+
+/**
+ * An utility function to get the opt with a given key . This function
+ * also print a readable message when no opts are found.
+ */
+std::string __testlib_keyToOpts(const std::string &key) {
+    auto it = __testlib_opts.find(key);
+    if (it == __testlib_opts.end())
+        __testlib_fail("Opts: unknown key '" + compress(key) + "'");
+    it->second.used = true;
+    return it->second.value;
+}
+
+template<typename T>
+T optValueToIntegral(const std::string &s, bool nonnegative);
+
+long double optValueToLongDouble(const std::string &s);
+
+std::string parseExponentialOptValue(const std::string &s) {
+    size_t pos = std::string::npos;
+    for (size_t i = 0; i < s.length(); i++)
+        if (s[i] == 'e' || s[i] == 'E') {
+            if (pos != std::string::npos)
+                __testlib_fail("Opts: expected typical exponential notation but '" + compress(s) + "' found");
+            pos = i;
+        }
+    if (pos == std::string::npos)
+        return s;
+    std::string e = s.substr(pos + 1);
+    if (!e.empty() && e[0] == '+')
+        e = e.substr(1);
+    if (e.empty())
+        __testlib_fail("Opts: expected typical exponential notation but '" + compress(s) + "' found");
+    if (e.length() > 20)
+        __testlib_fail("Opts: expected typical exponential notation but '" + compress(s) + "' found");
+    int ne = optValueToIntegral<int>(e, false);
+    std::string num = s.substr(0, pos);
+    if (num.length() > 20)
+        __testlib_fail("Opts: expected typical exponential notation but '" + compress(s) + "' found");
+    if (!num.empty() && num[0] == '+')
+        num = num.substr(1);
+    optValueToLongDouble(num);
+    bool minus = false;
+    if (num[0] == '-') {
+        minus = true;
+        num = num.substr(1);
+    }
+    for (int i = 0; i < +ne; i++) {
+        size_t sep = num.find('.');
+        if (sep == std::string::npos)
+            num += '0';
+        else {
+            if (sep + 1 == num.length())
+                num[sep] = '0';
+            else
+                std::swap(num[sep], num[sep + 1]);
+        }
+    }
+    for (int i = 0; i < -ne; i++) {
+        size_t sep = num.find('.');
+        if (sep == std::string::npos)
+            num.insert(num.begin() + int(num.length()) - 1, '.');
+        else {
+            if (sep == 0)
+                num.insert(num.begin() + 1, '0');
+            else
+                std::swap(num[sep - 1], num[sep]);
+        }
+    }
+    while (!num.empty() && num[0] == '0')
+        num = num.substr(1);
+    while (num.find('.') != std::string::npos && num.back() == '0')
+        num = num.substr(0, num.length() - 1);
+    if (!num.empty() && num.back() == '.')
+        num = num.substr(0, num.length() - 1);
+    if ((!num.empty() && num[0] == '.') || num.empty())
+        num.insert(num.begin(), '0');
+    return (minus ? "-" : "") + num;
+}
+
+template<typename T>
+T optValueToIntegral(const std::string &s_, bool nonnegative) {
+    std::string s(parseExponentialOptValue(s_));
+    if (s.empty())
+        __testlib_fail("Opts: expected integer but '" + compress(s_) + "' found");
+    T value = 0;
+    long double about = 0.0;
+    signed char sign = +1;
+    size_t pos = 0;
+    if (s[pos] == '-') {
+        if (nonnegative)
+            __testlib_fail("Opts: expected non-negative integer but '" + compress(s_) + "' found");
+        sign = -1;
+        pos++;
+    }
+    for (size_t i = pos; i < s.length(); i++) {
+        if (s[i] < '0' || s[i] > '9')
+            __testlib_fail("Opts: expected integer but '" + compress(s_) + "' found");
+        value = T(value * 10 + s[i] - '0');
+        about = about * 10 + s[i] - '0';
+    }
+    value *= sign;
+    about *= sign;
+    if (fabsl(value - about) > 0.1)
+        __testlib_fail("Opts: integer overflow: expected integer but '" + compress(s_) + "' found");
+    return value;
+}
+
+long double optValueToLongDouble(const std::string &s_) {
+    std::string s(parseExponentialOptValue(s_));
+    if (s.empty())
+        __testlib_fail("Opts: expected float number but '" + compress(s_) + "' found");
+    long double value = 0.0;
+    signed char sign = +1;
+    size_t pos = 0;
+    if (s[pos] == '-') {
+        sign = -1;
+        pos++;
+    }
+    bool period = false;
+    long double mul = 1.0;
+    for (size_t i = pos; i < s.length(); i++) {
+        if (s[i] == '.') {
+            if (period)
+                __testlib_fail("Opts: expected float number but '" + compress(s_) + "' found");
+            else {
+                period = true;
+                continue;
+            }
+        }
+        if (period)
+            mul *= 10.0;
+        if (s[i] < '0' || s[i] > '9')
+            __testlib_fail("Opts: expected float number but '" + compress(s_) + "' found");
+        if (period)
+            value += (s[i] - '0') / mul;
+        else
+            value = value * 10 + s[i] - '0';
+    }
+    value *= sign;
+    return value;
+}
+
+/**
+ * Return true if there is an opt with a given key.
+ * 
+ * By calling this function, automatic ensurement for no unused opts will be
+ * done when the program is finalized. Call suppressEnsureNoUnusedOpts() to
+ * turn it off.
+ */
+bool has_opt(const std::string &key) {
+    __testlib_ensureNoUnusedOptsFlag = true;
+    return __testlib_opts.count(key) != 0;
+}
+
+/* About the following part for opt with 2 and 3 arguments.
+ * 
+ * To parse the argv/opts correctly for a give type (integer, floating point or
+ * string), some meta programming must be done to determine the type of
+ * the type, and use the correct parsing function accordingly.
+ * 
+ * The pseudo algorithm for determining the type of T and parse it accordingly
+ * is as follows:
+ * 
+ * if (T is integral type) {
+ *   if (T is unsigned) {
+ *     parse the argv/opt as an **unsigned integer** of type T.
+ *   } else {
+ *     parse the argv/opt as an **signed integer** of type T.
+ * } else {
+ *   if (T is floating point type) {
+ *     parse the argv/opt as an **floating point** of type T.
+ *   } else {
+ *     // T should be std::string
+ *     just the raw content of the argv/opts.
+ *   }
+ * }
+ * 
+ * To help with meta programming, some `opt` function with 2 or 3 arguments are
+ * defined.
+ * 
+ * Opt with 3 arguments:    T opt(true/false is_integral, true/false is_unsigned, index/key)
+ * 
+ *   + The first argument is for determining whether the type T is an integral
+ *   type. That is, the result of std::is_integral<T>() should be passed to
+ *   this argument. When false, the type _should_ be either floating point or a
+ *   std::string.
+ *   
+ *   + The second argument is for determining whether the signedness of the type
+ *   T (if it is unsigned or signed). That is, the result of
+ *   std::is_unsigned<T>() should be passed to this argument. This argument can
+ *   be ignored if the first one is false, because it only applies to integer.
+ *
+ * Opt with 2 arguments:    T opt(true/false is_floating_point, index/key)
+ *   + The first argument is for determining whether the type T is a floating
+ *   point type. That is, the result of std::is_floating_point<T>() should be
+ *   passed to this argument. When false, the type _should_ be a std::string.
+ */
+
+template<typename T>
+T opt(std::false_type is_floating_point, int index);
+
+template<>
+std::string opt(std::false_type /*is_floating_point*/, int index) {
+    return __testlib_indexToArgv(index);
+}
+
+template<typename T>
+T opt(std::true_type /*is_floating_point*/, int index) {
+    return T(optValueToLongDouble(__testlib_indexToArgv(index)));
+}
+
+template<typename T, typename U>
+T opt(std::false_type /*is_integral*/, U /*is_unsigned*/, int index) {
+    return opt<T>(std::is_floating_point<T>(), index);
+}
+
+template<typename T>
+T opt(std::true_type /*is_integral*/, std::false_type /*is_unsigned*/, int index) {
+    return optValueToIntegral<T>(__testlib_indexToArgv(index), false);
+}
+
+template<typename T>
+T opt(std::true_type /*is_integral*/, std::true_type /*is_unsigned*/, int index) {
+    return optValueToIntegral<T>(__testlib_indexToArgv(index), true);
+}
+
+template<>
+bool opt(std::true_type /*is_integral*/, std::true_type /*is_unsigned*/, int index) {
+    std::string value = __testlib_indexToArgv(index);
+    if (value == "true" || value == "1")
+        return true;
+    if (value == "false" || value == "0")
+        return false;
+    __testlib_fail("Opts: opt by index '" + toString(index) + "': expected bool true/false or 0/1 but '"
+            + compress(value) + "' found");
+}
+
+/**
+ * Return the parsed argv by a given index.
+ */
+template<typename T>
+T opt(int index) {
+    return opt<T>(std::is_integral<T>(), std::is_unsigned<T>(), index);
+}
+
+/**
+ * Return the raw string value of an argv by a given index.
+ */
+std::string opt(int index) {
+    return opt<std::string>(index);
+}
+
+/**
+ * Return the parsed argv by a given index. If the index is bigger than
+ * the number of argv, return the given default_value.
+ */
+template<typename T>
+T opt(int index, const T &default_value) {
+    if (index >= int(__testlib_argv.size())) {
+        return default_value;
+    }
+    return opt<T>(index);
+}
+
+/**
+ * Return the raw string value of an argv by a given index. If the index is
+ * bigger than the number of argv, return the given default_value.
+ */
+std::string opt(int index, const std::string &default_value) {
+    return opt<std::string>(index, default_value);
+}
+
+template<typename T>
+T opt(std::false_type is_floating_point, const std::string &key);
+
+template<>
+std::string opt(std::false_type /*is_floating_point*/, const std::string &key) {
+    return __testlib_keyToOpts(key);
+}
+
+template<typename T>
+T opt(std::true_type /*is_integral*/, const std::string &key) {
+    return T(optValueToLongDouble(__testlib_keyToOpts(key)));
+}
+
+template<typename T, typename U>
+T opt(std::false_type /*is_integral*/, U, const std::string &key) {
+    return opt<T>(std::is_floating_point<T>(), key);
+}
+
+template<typename T>
+T opt(std::true_type /*is_integral*/, std::false_type /*is_unsigned*/, const std::string &key) {
+    return optValueToIntegral<T>(__testlib_keyToOpts(key), false);
+}
+
+template<typename T>
+T opt(std::true_type /*is_integral*/, std::true_type /*is_unsigned*/, const std::string &key) {
+    return optValueToIntegral<T>(__testlib_keyToOpts(key), true);
+}
+
+template<>
+bool opt(std::true_type /*is_integral*/, std::true_type /*is_unsigned*/, const std::string &key) {
+    if (!has_opt(key))
+        return false;
+    std::string value = __testlib_keyToOpts(key);
+    if (value == "true" || value == "1")
+        return true;
+    if (value == "false" || value == "0")
+        return false;
+    __testlib_fail("Opts: key '" + compress(key) + "': expected bool true/false or 0/1 but '"
+        + compress(value) + "' found");
+}
+
+/**
+ * Return the parsed opt by a given key.
+ */
+template<typename T>
+T opt(const std::string &key) {
+    return opt<T>(std::is_integral<T>(), std::is_unsigned<T>(), key);
+}
+
+/**
+ * Return the raw string value of an opt by a given key
+ */
+std::string opt(const std::string &key) {
+    return opt<std::string>(key);
+}
+
+/* Scorer started. */
+
+enum TestResultVerdict {
+    SKIPPED,
+    OK,
+    WRONG_ANSWER,
+    RUNTIME_ERROR,
+    TIME_LIMIT_EXCEEDED,
+    IDLENESS_LIMIT_EXCEEDED,
+    MEMORY_LIMIT_EXCEEDED,
+    COMPILATION_ERROR,
+    CRASHED,
+    FAILED
+};
+
+std::string serializeVerdict(TestResultVerdict verdict) {
+    switch (verdict) {
+        case SKIPPED: return "SKIPPED";
+        case OK: return "OK";
+        case WRONG_ANSWER: return "WRONG_ANSWER";
+        case RUNTIME_ERROR: return "RUNTIME_ERROR";
+        case TIME_LIMIT_EXCEEDED: return "TIME_LIMIT_EXCEEDED";
+        case IDLENESS_LIMIT_EXCEEDED: return "IDLENESS_LIMIT_EXCEEDED";
+        case MEMORY_LIMIT_EXCEEDED: return "MEMORY_LIMIT_EXCEEDED";
+        case COMPILATION_ERROR: return "COMPILATION_ERROR";
+        case CRASHED: return "CRASHED";
+        case FAILED: return "FAILED";
+    }
+    throw "Unexpected verdict";
+}
+
+TestResultVerdict deserializeTestResultVerdict(std::string s) {
+    if (s == "SKIPPED")
+        return SKIPPED;
+    else if (s == "OK")
+        return OK;
+    else if (s == "WRONG_ANSWER")
+        return WRONG_ANSWER;
+    else if (s == "RUNTIME_ERROR")
+        return RUNTIME_ERROR;
+    else if (s == "TIME_LIMIT_EXCEEDED")
+        return TIME_LIMIT_EXCEEDED;
+    else if (s == "IDLENESS_LIMIT_EXCEEDED")
+        return IDLENESS_LIMIT_EXCEEDED;
+    else if (s == "MEMORY_LIMIT_EXCEEDED")
+        return MEMORY_LIMIT_EXCEEDED;
+    else if (s == "COMPILATION_ERROR")
+        return COMPILATION_ERROR;
+    else if (s == "CRASHED")
+        return CRASHED;
+    else if (s == "FAILED")
+        return FAILED;
+    ensuref(false, "Unexpected serialized TestResultVerdict");
+    // No return actually.
+    return FAILED;
+}
+
+struct TestResult {
+    int testIndex;
+    std::string testset;
+    std::string group;
+    TestResultVerdict verdict;
+    double points;
+    long long timeConsumed;
+    long long memoryConsumed;
+    std::string input;
+    std::string output;
+    std::string answer;
+    int exitCode;
+    std::string checkerComment;
+};
+
+std::string serializePoints(double points) {
+    if (std::isnan(points))
+        return "";
+    else {
+        char c[64];
+        snprintf(c, 64, "%.03lf", points);
+        return c;
+    }
+}
+
+double deserializePoints(std::string s) {
+    if (s.empty())
+        return std::numeric_limits<double>::quiet_NaN();
+    else {
+        double result;
+#ifdef _MSC_VER
+        ensuref(sscanf_s(s.c_str(), "%lf", &result) == 1, "Invalid serialized points");
+#else
+        ensuref(std::sscanf(s.c_str(), "%lf", &result) == 1, "Invalid serialized points");
+#endif
+        return result;
+    }                                              
+}
+
+std::string escapeTestResultString(std::string s) {
+    std::string result;
+    for (size_t i = 0; i < s.length(); i++) {
+        if (s[i] == '\r')
+            continue;
+        if (s[i] == '\n') {
+            result += "\\n";
+            continue;
+        }
+        if (s[i] == '\\' || s[i] == ';')
+            result += '\\';
+        result += s[i];
+    }
+    return result;
+}
+
+std::string unescapeTestResultString(std::string s) {
+    std::string result;
+    for (size_t i = 0; i < s.length(); i++) {
+        if (s[i] == '\\' && i + 1 < s.length()) {
+            if (s[i + 1] == 'n') {
+                result += '\n';
+                i++;
+                continue;
+            } else if (s[i + 1] == ';' || s[i + 1] == '\\') {
+                result += s[i + 1];
+                i++;
+                continue;
+            }
+        }
+        result += s[i];
+    }
+    return result;
+}
+
+std::string serializeTestResult(TestResult tr) {
+    std::string result;
+    result += std::to_string(tr.testIndex);
+    result += ";";
+    result += escapeTestResultString(tr.testset);
+    result += ";";
+    result += escapeTestResultString(tr.group);
+    result += ";";
+    result += serializeVerdict(tr.verdict);
+    result += ";";
+    result += serializePoints(tr.points);
+    result += ";";
+    result += std::to_string(tr.timeConsumed);
+    result += ";";
+    result += std::to_string(tr.memoryConsumed);
+    result += ";";
+    result += escapeTestResultString(tr.input);
+    result += ";";
+    result += escapeTestResultString(tr.output);
+    result += ";";
+    result += escapeTestResultString(tr.answer);
+    result += ";";
+    result += std::to_string(tr.exitCode);
+    result += ";";
+    result += escapeTestResultString(tr.checkerComment);
+    return result;
+}
+
+TestResult deserializeTestResult(std::string s) {
+    std::vector<std::string> items;
+    std::string t;
+    for (size_t i = 0; i < s.length(); i++) {
+        if (s[i] == '\\') {
+            t += s[i];
+            if (i + 1 < s.length())
+                t += s[i + 1];
+            i++;
+            continue;
+        } else {
+            if (s[i] == ';') {
+                items.push_back(t);
+                t = "";
+            } else
+                t += s[i];
+        }
+    }
+    items.push_back(t);
+
+    ensuref(items.size() == 12, "Invalid TestResult serialization: expected exactly 12 items");
+    
+    TestResult tr;
+    size_t pos = 0;
+    tr.testIndex = stoi(items[pos++]);
+    tr.testset = unescapeTestResultString(items[pos++]);
+    tr.group = unescapeTestResultString(items[pos++]);
+    tr.verdict = deserializeTestResultVerdict(items[pos++]);
+    tr.points = deserializePoints(items[pos++]);
+    tr.timeConsumed = stoll(items[pos++]);
+    tr.memoryConsumed = stoll(items[pos++]);
+    tr.input = unescapeTestResultString(items[pos++]);
+    tr.output = unescapeTestResultString(items[pos++]);
+    tr.answer = unescapeTestResultString(items[pos++]);
+    tr.exitCode = stoi(items[pos++]);
+    tr.checkerComment = unescapeTestResultString(items[pos++]);
+    
+    return tr;
+}
+
+std::vector<TestResult> readTestResults(std::string fileName) {
+    std::ifstream stream;
+    stream.open(fileName.c_str(), std::ios::in);
+    ensuref(stream.is_open(), "Can't read test results file '%s'", fileName.c_str());
+    std::vector<TestResult> result;
+    std::string line;
+    while (getline(stream, line))
+        if (!line.empty())
+            result.push_back(deserializeTestResult(line));
+    stream.close();
+    return result;
+}
+
+std::function<double(std::vector<TestResult>)> __testlib_scorer;
+
+struct TestlibScorerGuard {
+    ~TestlibScorerGuard() {
+        if (testlibMode == _scorer) {
+            std::vector<TestResult> testResults;
+            while (!inf.eof()) {
+                std::string line = inf.readLine();
+                if (!line.empty())
+                    testResults.push_back(deserializeTestResult(line));
+            }
+            inf.readEof();
+            printf("%.3f\n", __testlib_scorer(testResults));
+        }
+    }
+} __testlib_scorer_guard;
+
+void registerScorer(int argc, char *argv[], std::function<double(std::vector<TestResult>)> scorer) {
+    /* Suppress unused. */
+    (void)(argc), (void)(argv);
+
+    __testlib_ensuresPreconditions();
+
+    testlibMode = _scorer;
+    __testlib_set_binary(stdin);
+
+    inf.init(stdin, _input);
+    inf.strict = false;
+
+    __testlib_scorer = scorer;
+}
+
+/* Scorer ended. */
+
+/**
+ * Return the parsed opt by a given key. If no opts with the given key are
+ * found, return the given default_value.
+ * 
+ * By calling this function, automatic ensurement for no unused opts will be
+ * done when the program is finalized. Call suppressEnsureNoUnusedOpts() to
+ * turn it off.
+ */
+template<typename T>
+T opt(const std::string &key, const T &default_value) {
+    if (!has_opt(key)) {
+        return default_value;
+    }
+    return opt<T>(key);
+}
+
+/**
+ * Return the raw string value of an opt by a given key. If no opts with the
+ * given key are found, return the given default_value.
+ * 
+ * By calling this function, automatic ensurement for no unused opts will be
+ * done when the program is finalized. Call suppressEnsureNoUnusedOpts() to
+ * turn it off.
+ */
+std::string opt(const std::string &key, const std::string &default_value) {
+    return opt<std::string>(key, default_value);
+}
+
+/**
+ * Check if all opts are used. If not, __testlib_fail is called.
+ * Should be used after calling all opt() function calls.
+ * 
+ * This function is useful when opt() with default_value for checking typos
+ * in the opt's key.
+ */
+void ensureNoUnusedOpts() {
+    for (const auto &opt: __testlib_opts) {
+        if (!opt.second.used) {
+            __testlib_fail(testlib_format_("Opts: unused key '%s'", compress(opt.first).c_str()));
+        }
+    }
+}
+
+void suppressEnsureNoUnusedOpts() {
+    __testlib_ensureNoUnusedOptsSuppressed = true;
+}
+
+void TestlibFinalizeGuard::autoEnsureNoUnusedOpts() {
+    if (__testlib_ensureNoUnusedOptsFlag && !__testlib_ensureNoUnusedOptsSuppressed) {
+        ensureNoUnusedOpts();
+    }
+}
+
+TestlibFinalizeGuard testlibFinalizeGuard;
+#endif
+
+#ifdef __GNUC__
+__attribute__ ((format (printf, 1, 2)))
+#endif
+std::string testlib_format_(const char *fmt, ...) {
+    FMT_TO_RESULT(fmt, fmt, result);
+    return result;
+}
+
+std::string testlib_format_(const std::string fmt, ...) {
+    FMT_TO_RESULT(fmt, fmt.c_str(), result);
+    return result;
+}
+
+#if (__cplusplus >= 202002L && __has_include(<format>)) || __cpp_lib_format
+template <typename... Args>
+std::string format(const char* fmt, Args&&... args) {
+    size_t size = size_t(std::snprintf(nullptr, 0, fmt, args...) + 1);
+    std::vector<char> buffer(size);
+    std::snprintf(buffer.data(), size, fmt, args...);
+    return std::string(buffer.data());
+}
+
+template <typename... Args>
+std::string format(const std::string fmt, Args&&... args) {
+    size_t size = size_t(std::snprintf(nullptr, 0, fmt.c_str(), args...) + 1);
+    std::vector<char> buffer(size);
+    std::snprintf(buffer.data(), size, fmt.c_str(), args...);
+    return std::string(buffer.data());
+}
+#else
+#ifdef __GNUC__
+__attribute__ ((format (printf, 1, 2)))
+#endif
+std::string format(const char *fmt, ...) {
+    FMT_TO_RESULT(fmt, fmt, result);
+    return result;
+}
+
+std::string format(const std::string fmt, ...) {
+    FMT_TO_RESULT(fmt, fmt.c_str(), result);
+    return result;
+}
+#endif
+
+#endif
diff --git a/packages/result-handler/src/services/result.services.ts b/packages/result-handler/src/services/result.services.ts
index d75e573c..da6c341f 100644
--- a/packages/result-handler/src/services/result.services.ts
+++ b/packages/result-handler/src/services/result.services.ts
@@ -1,5 +1,5 @@
-import { fetchContestProblem, fetchDomainProblem, fetchSubmission, judgerExchange, judgerTasksKey, rabbitMQ, ranklistRedis, recalculateTeamTotalScore, submissionCollection, teamScoreCollection } from '@argoncs/common'
-import { type CompilingResult, CompilingStatus, type GradingResult, GradingStatus, type GradingTask, JudgerTaskType, type Problem, SubmissionStatus } from '@argoncs/types'
+import { fetchContestProblem, fetchDomainProblem, fetchSubmission, judgerExchange, judgerTasksKey, rabbitMQ, ranklistRedis, recalculateTeamTotalScore, submissionCollection, teamScoreCollection, domainProblemCollection } from '@argoncs/common'
+import { type CompilingResult, CompilingStatus, type GradingResult, GradingStatus, type GradingTask, JudgerTaskType, type Problem, SubmissionStatus, type CompilingCheckerResult  } from '@argoncs/types' /*=*/
 import { NotFoundError } from 'http-errors-enhanced'
 import path from 'path'
 
@@ -8,33 +8,43 @@ export async function handleCompileResult (compileResult: CompilingResult, submi
 
   if (submission.status === SubmissionStatus.Compiling) {
     if (compileResult.status === CompilingStatus.Succeeded) {
-      let problem: Problem
-      if (submission.contestId == null) {
-        const { problemId, domainId } = submission
-        problem = await fetchDomainProblem({ problemId, domainId })
-      } else {
-        const { problemId, contestId } = submission
-        problem = await fetchContestProblem({ problemId, contestId })
-      }
-      const submissionTestcases: Array<{ points: number, input: { name: string, versionId: string }, output: { name: string, versionId: string } }> = []
+      const { problemId, domainId, contestId } = submission
+      let problem: Problem = contestId == null ?
+        await fetchDomainProblem({ problemId, domainId }) : 
+        await fetchContestProblem({ problemId, contestId })
+
       if (problem.testcases == null) {
-        await completeGrading(submissionId, 'Problem does not have testcases'); return
+        await completeGrading(submissionId, 'Problem does not have testcases');
+        return
       }
+
+      if (problem.checker === null || problem.checker === undefined) {
+        await completeGrading(submissionId, 'Problem Checker does not exist or is not compiled');
+        return
+      }
+
+      const submissionTestcases: Array<{ points: number, input: { name: string, versionId: string }, output: { name: string, versionId: string } }> = []
+
       problem.testcases.forEach((testcase, index) => {
         const task: GradingTask = {
           constraints: problem.constraints,
           type: JudgerTaskType.Grading,
           submissionId,
+          problemId: problem.id,
           testcase: {
             input: {
-              objectName: path.join(problem.domainId, problem.id, testcase.input.name),
+              objectName: path.join(problem.id, testcase.input.name),
               versionId: testcase.input.versionId
             },
             output: {
-              objectName: path.join(problem.domainId, problem.id, testcase.output.name),
+              objectName: path.join(problem.id, testcase.output.name),
               versionId: testcase.output.versionId
             }
           },
+          checker: { 
+            objectName: problem.checker!.name,
+            versionId: problem.checker!.versionId 
+          },
           testcaseIndex: index,
           language: submission.language
         }
@@ -126,3 +136,16 @@ export async function handleGradingResult (gradingResult: GradingResult, submiss
     }
   }
 }
+
+export async function handleCompileCheckerResult (result: CompilingCheckerResult, problemId: string): Promise<void> {
+
+  if (result.status == CompilingStatus.Failed) {
+    // TODO: warn of broken checker
+    console.log('checker compilation failed')
+    return
+  }
+
+  const checker = result.checker;
+  console.log('checker compilation result recieved: ', checker);
+  await domainProblemCollection.updateOne({ id: problemId }, { $set: { checker }});
+}
diff --git a/packages/result-handler/src/start.ts b/packages/result-handler/src/start.ts
index de110f0e..c9624beb 100644
--- a/packages/result-handler/src/start.ts
+++ b/packages/result-handler/src/start.ts
@@ -1,7 +1,8 @@
 import { connectMongoDB, connectRabbitMQ, connectRanklistRedis, deadResultsQueue, deadTasksQueue, judgerResultsQueue, rabbitMQ, sentry } from '@argoncs/common'
-import { type CompilingResultMessage, type CompilingTask, type GradingResultMessage, type GradingTask, JudgerResultType } from '@argoncs/types'
+import { type CompilingResultMessage, type CompilingTask, type GradingResultMessage, type GradingTask, JudgerResultType, CompilingCheckerResultMessage } from '@argoncs/types'
 import assert from 'assert'
-import { completeGrading, handleCompileResult, handleGradingResult } from './services/result.services.js'
+import { completeGrading, handleCompileCheckerResult, handleCompileResult, handleGradingResult } from './services/result.services.js'
+/*=*/
 
 sentry.init({
   dsn: 'https://f56d872b49cc4981baf851fd569080cd@o1044666.ingest.sentry.io/450531102457856',
@@ -11,10 +12,11 @@ sentry.init({
 
 export async function startHandler (): Promise<void> {
   assert(process.env.RABBITMQ_URL != null)
-  await connectRabbitMQ(process.env.RABBITMQ_URL)
   assert(process.env.MONGO_URL != null)
-  await connectMongoDB(process.env.MONGO_URL)
   assert(process.env.RANKLISTREDIS_URL != null)
+
+  await connectRabbitMQ(process.env.RABBITMQ_URL)
+  await connectMongoDB(process.env.MONGO_URL)
   await connectRanklistRedis(process.env.RANKLISTREDIS_URL)
 
   // eslint-disable-next-line @typescript-eslint/no-misused-promises
@@ -22,17 +24,23 @@ export async function startHandler (): Promise<void> {
     console.log('judger result queue consumed');
     if (message != null) {
       try {
-        const resultMessage: CompilingResultMessage | GradingResultMessage = JSON.parse(message.content.toString())
+        const result: CompilingCheckerResultMessage | CompilingResultMessage | GradingResultMessage = 
+          JSON.parse(message.content.toString())
 
-        if (resultMessage.type === JudgerResultType.Compiling) {
-          await handleCompileResult(resultMessage.result, resultMessage.submissionId)
-        } else if (resultMessage.type === JudgerResultType.Grading) {
-          await handleGradingResult(resultMessage.result, resultMessage.submissionId, resultMessage.testcaseIndex)
-        } else {
+        if (result.type === JudgerResultType.Compiling)
+          await handleCompileResult(result.result, result.submissionId)
+
+        else if (result.type === JudgerResultType.Grading)
+          await handleGradingResult(result.result, result.submissionId, result.testcaseIndex)
+
+        else if (result.type === JudgerResultType.CompilingChecker)
+          await handleCompileCheckerResult(result.result, result.problemId)
+
+        else 
           throw Error('Invalid result type')
-        }
 
         rabbitMQ.ack(message)
+
       } catch (err) {
         sentry.captureException(err)
         rabbitMQ.reject(message, false)
@@ -45,9 +53,14 @@ export async function startHandler (): Promise<void> {
     console.log('dead results queue consumed')
     if (message != null) {
       try {
-        const letter: CompilingResultMessage | GradingResultMessage = JSON.parse(message.content.toString())
+        const result: CompilingCheckerResultMessage | CompilingResultMessage | GradingResultMessage =
+          JSON.parse(message.content.toString())
 
-        await completeGrading(letter.submissionId, 'One or more of the grading results failed to be processed')
+        if (result.type === JudgerResultType.CompilingChecker)
+          // TODO: find a better way to notify this
+          console.log('checker compilation message failed to be acknowledged. weird')
+        else 
+          await completeGrading(result.submissionId, 'One or more of the grading results failed to be processed')
         rabbitMQ.ack(message)
       } catch (err) {
         sentry.captureException(err)
diff --git a/packages/types/src/types/compilation.types.ts b/packages/types/src/types/compilation.types.ts
index c3d582f7..cd63438e 100644
--- a/packages/types/src/types/compilation.types.ts
+++ b/packages/types/src/types/compilation.types.ts
@@ -50,3 +50,25 @@ export interface CompilingResultMessage {
   submissionId: string
   result: CompilingResult
 }
+
+export interface CompilingCheckerTask {
+  type: JudgerTaskType.CompilingChecker,
+  source: string,
+  problemId: string,
+}
+
+export const CompilingCheckerSucceededSchema = Type.Object({
+  status: Type.Literal(CompilingStatus.Succeeded),
+  checker: Type.Object({ name: Type.String(), versionId: Type.String() })
+})
+export type CompilingChekcerSucceeded = Static<typeof CompileSucceededSchema>
+
+// When using Type.Union, all children should not have addtionalProperties: false set to avoid an ajv issue
+export const CompilingCheckerResultSchema = Type.Union([CompilingCheckerSucceededSchema, CompileFailedSchema])
+export type CompilingCheckerResult = Static<typeof CompilingCheckerResultSchema>
+
+export interface CompilingCheckerResultMessage {
+  type: JudgerResultType.CompilingChecker
+  problemId: string
+  result: CompilingCheckerResult 
+}
diff --git a/packages/types/src/types/grading.types.ts b/packages/types/src/types/grading.types.ts
index e394a7f0..ffafbfea 100644
--- a/packages/types/src/types/grading.types.ts
+++ b/packages/types/src/types/grading.types.ts
@@ -1,4 +1,4 @@
-import { type SubmissionLang } from './compilation.types.js'
+import { type SubmissionLang } from './compilation.types.js' /*=*/
 
 import {
   type Constraints,
@@ -8,9 +8,9 @@ import {
   SandboxRuntimeErrorSchema,
   SandboxSystemErrorSchema,
   SandboxTimeExceededSchema
-} from './judger.types.js'
+} from './judger.types.js' /*=*/
 
-import { type Static, Type } from '@sinclair/typebox'
+import { type Static, Type } from '@sinclair/typebox' /*=*/
 
 export enum GradingStatus {
   Accepted = 'AC',
@@ -20,6 +20,8 @@ export enum GradingStatus {
 export interface GradingTask {
   type: JudgerTaskType.Grading
   submissionId: string
+  problemId: string
+  checker: { objectName: string, versionId: string }
   testcase: {
     input: { objectName: string, versionId: string }
     output: { objectName: string, versionId: string }
diff --git a/packages/types/src/types/judger.types.ts b/packages/types/src/types/judger.types.ts
index 8c4cd69a..f174cfbd 100644
--- a/packages/types/src/types/judger.types.ts
+++ b/packages/types/src/types/judger.types.ts
@@ -3,11 +3,13 @@ import { type Static, Type } from '@sinclair/typebox'
 export enum JudgerTaskType {
   Compiling = 'Compiling',
   Grading = 'Grading',
+  CompilingChecker = 'CompilingChecker'
 }
 
 export enum JudgerResultType {
   Compiling = 'Compiling',
   Grading = 'Grading',
+  CompilingChecker = 'CompilingChecker'
 }
 
 export enum SandboxStatus {
diff --git a/packages/types/src/types/problem.types.ts b/packages/types/src/types/problem.types.ts
index 0e25ba0d..c00bc107 100644
--- a/packages/types/src/types/problem.types.ts
+++ b/packages/types/src/types/problem.types.ts
@@ -38,7 +38,7 @@ export const ProblemSchema = Type.Object({
       points: Type.Number()
     }))
   ),
-
+  checker: Type.Optional(Type.Object({ name: Type.String(), versionId: Type.String() })),
   id: Type.String(),
   domainId: Type.String()
 })
diff --git a/packages/upload-server/src/routes/testcase.routes.ts b/packages/upload-server/src/routes/testcase.routes.ts
index 9c727efc..76ad73d5 100644
--- a/packages/upload-server/src/routes/testcase.routes.ts
+++ b/packages/upload-server/src/routes/testcase.routes.ts
@@ -1,10 +1,9 @@
 import { consumeUploadSession, uploadTestcase } from '../services/testcase.services.js'
-import { uploadPolygon } from '../services/polygon.services.js'
 
 import { Type } from '@sinclair/typebox'
 import multipart from '@fastify/multipart'
 import { type FastifyTypeBox } from '../types.js'
-import { BadRequestError, badRequestSchema, PayloadTooLargeError, unauthorizedSchema } from 'http-errors-enhanced'
+import { BadRequestError, badRequestSchema, PayloadTooLargeError, unauthorizedSchema } from 'http-errors-enhanced' /*=*/
 
 export async function testcaseRoutes (routes: FastifyTypeBox): Promise<void> {
   await routes.register(multipart.default, {
@@ -38,7 +37,11 @@ export async function testcaseRoutes (routes: FastifyTypeBox): Promise<void> {
         const testcases = request.files()
         const queue: Array<Promise<{ versionId: string, name: string }>> = []
         for await (const testcase of testcases) {
-          queue.push(uploadTestcase(domainId, problemId, testcase))
+          queue.push(uploadTestcase({
+            problemId, 
+            filename: testcase.filename.replaceAll('/', '.'),
+            stream: testcase.file
+          }))
         }
         return await reply.status(201).send(await Promise.all(queue))
       } catch (err) {
diff --git a/packages/upload-server/src/services/polygon.services.ts b/packages/upload-server/src/services/polygon.services.ts
index 29232d56..16a986db 100644
--- a/packages/upload-server/src/services/polygon.services.ts
+++ b/packages/upload-server/src/services/polygon.services.ts
@@ -1,13 +1,13 @@
-import { uploadFile } from './testcase.services.js'
+import { uploadTestcase } from './testcase.services.js'
 import { nanoid } from 'nanoid'
-import { Problem, type Constraints, type NewProblem } from '@argoncs/types'
-import { type MultipartFile } from '@fastify/multipart'
+import { CompilingCheckerTask, JudgerTaskType, Problem, type Constraints, type NewProblem } from '@argoncs/types' /*=*/
+import { type MultipartFile } from '@fastify/multipart' /*=*/
 import { exec as exec_sync } from 'node:child_process'
 import { promisify } from 'node:util'
 import fs from 'node:fs/promises'
 import path from 'node:path'
 import { BadRequestError } from 'http-errors-enhanced'
-import { domainProblemCollection } from '@argoncs/common'
+import { domainProblemCollection, judgerTasksKey, judgerExchange, rabbitMQ } from '@argoncs/common'
 
 const exec = promisify(exec_sync)
 
@@ -23,11 +23,11 @@ export async function uploadPolygon ({ domainId, archive }: { domainId: string,
 
   // Unzip Archive
   const archive_path = path.join(work_path, 'archive')
-  const { stderr } = await exec(`unzip ${archive_path} -d ${work_path}`)
-
-  if (stderr) {
-    console.log(stderr)
-    throw new BadRequestError('Could not unzip package archive')
+  try {
+    await exec(`unzip ${archive_path} -d ${work_path}`)
+  } catch (err) {
+    console.log(err)
+    throw new BadRequestError(`Could not unzip package archive: ${err}`)
   }
   console.log(`== Finished Unzipping. ${archive_path} => ${work_path}`)
 
@@ -70,8 +70,8 @@ export async function uploadPolygon ({ domainId, archive }: { domainId: string,
     const input_file = await fs.open(path.join(work_path, 'tests', name))
     const output_file = await fs.open(path.join(work_path, 'tests', name + '.a'))
 
-    const input = await uploadFile(domainId, problem.id, name, input_file.createReadStream())
-    const output = await uploadFile(domainId, problem.id, name + '-ans', output_file.createReadStream())
+    const input = await uploadTestcase({problemId:problem.id, filename: name, stream: input_file.createReadStream()})
+    const output = await uploadTestcase({problemId: problem.id, filename: name + '-ans', stream: output_file.createReadStream()})
 
     problem.testcases.push({
       input,
@@ -79,14 +79,23 @@ export async function uploadPolygon ({ domainId, archive }: { domainId: string,
       points: 100 / test_n
     })
   }
-  /* Cleanup working directory */
-  await exec(`rm -rf ${work_path}`)
-
   console.log('problem: ', problem)
 
   // Update problem
   // Assuming the token is correct, the problem must exist.
   await domainProblemCollection.insertOne(problem)
 
+  // Compile checker
+  const checkerSource = (await fs.readFile(path.join(work_path, 'check.cpp'))).toString()
+  const compileTask: CompilingCheckerTask = {
+    type: JudgerTaskType.CompilingChecker,
+    source: checkerSource,
+    problemId: problem.id
+  }
+  rabbitMQ.publish(judgerExchange, judgerTasksKey, Buffer.from(JSON.stringify(compileTask)))
+
+  // Cleanup working directory
+  await exec(`rm -rf ${work_path}`)
+
   return problem.id
 }
diff --git a/packages/upload-server/src/services/testcase.services.ts b/packages/upload-server/src/services/testcase.services.ts
index ced5a95a..d0dd0afc 100644
--- a/packages/upload-server/src/services/testcase.services.ts
+++ b/packages/upload-server/src/services/testcase.services.ts
@@ -1,27 +1,17 @@
 import { minio, uploadSessionCollection } from '@argoncs/common'
-import { type MultipartFile } from '@fastify/multipart'
+import { type MultipartFile } from '@fastify/multipart' /*=*/
 import { BadRequestError, UnauthorizedError } from 'http-errors-enhanced'
 import path from 'node:path'
 import type internal from 'node:stream'
 
-/* Uploads a MultipartFile to testcases. Warps 'uploadFile(..)' */
-export async function uploadTestcase (
-  domainId: string,
-  problemId: string,
-  testcase: MultipartFile
-): Promise<{ versionId: string, name: string }> {
-  const filename = testcase.filename.replaceAll('/', '.')
-  return await uploadFile(domainId, problemId, filename, testcase.file)
-}
 
 /* Uploads a single file into 'testcases' */
-export async function uploadFile (
-  domainId: string,
+export async function uploadTestcase ({ problemId, filename, stream }:{
   problemId: string,
   filename: string,
   stream: internal.Readable
-): Promise<{ versionId: string, name: string }> {
-  const objectName = path.join(domainId, problemId, filename)
+}): Promise<{ versionId: string, name: string }> {
+  const objectName = path.join(problemId, filename)
   const { versionId } = await minio.putObject('testcases', objectName, stream)
   if (versionId == null) {
     throw Error('Versioning not enabled on testcases bucket')
diff --git a/packages/upload-server/src/start.ts b/packages/upload-server/src/start.ts
index 2ad50edf..7fd18703 100644
--- a/packages/upload-server/src/start.ts
+++ b/packages/upload-server/src/start.ts
@@ -4,10 +4,10 @@ import fastifyHttpErrorsEnhanced from '@chenhongqiao/fastify-http-errors-enhance
 import fastifyAuth from '@fastify/auth'
 import fastifyCors from '@fastify/cors'
 
-import { testcaseRoutes } from './routes/testcase.routes.js'
+//import { testcaseRoutes } from './routes/testcase.routes.js'
 import { heartbeatRoutes } from './routes/heartbeat.routes.js'
 
-import { connectMinIO, connectMongoDB, sentry } from '@argoncs/common'
+import { connectMinIO, connectMongoDB, connectRabbitMQ, sentry } from '@argoncs/common'
 
 import fastifySensible from '@fastify/sensible'
 import assert from 'assert'
@@ -27,9 +27,12 @@ sentry.init({
 
 export async function startUploadServer (): Promise<void> {
   assert(process.env.MINIO_URL != null)
-  await connectMinIO(process.env.MINIO_URL)
   assert(process.env.MONGO_URL != null)
+  assert(process.env.RABBITMQ_URL != null)
+
+  await connectMinIO(process.env.MINIO_URL)
   await connectMongoDB(process.env.MONGO_URL)
+  await connectRabbitMQ(process.env.RABBITMQ_URL)
 
   await app.register(fastifyHttpErrorsEnhanced, {
     handle404Errors: false,
@@ -49,9 +52,9 @@ export async function startUploadServer (): Promise<void> {
     credentials: true
   })
 
-  await app.register(polygonRoutes, { prefix: '/polygon' })
-  await app.register(testcaseRoutes, { prefix: '/testcases' })
   await app.register(heartbeatRoutes, { prefix: '/heartbeat' })
+  await app.register(polygonRoutes, { prefix: '/polygon' })
+  //await app.register(testcaseRoutes, { prefix: '/testcases' })
 
   try {
     const port: number = parseInt(process.env.UPLOAD_SERVER_PORT ?? '8001')