diff --git a/Calculator/main.swift b/Calculator/main.swift
index c54202a..f5f089c 100644
--- a/Calculator/main.swift
+++ b/Calculator/main.swift
@@ -8,12 +8,20 @@
 
 import Foundation
 
-let text = readLine()
+let quit: [String] = ["q", "quit"]
 
-if let text = text {
+while true {
+    
+    print("> ", separator: "", terminator: "")
+    
+    let txt = readLine()
+    
+    guard let text = txt, !quit.contains(text.lowercased()) else {
+        break
+    }
+    
     let interpreter = Interpreter(text)
+    print(">> = ", separator: "", terminator: "")
     print(interpreter.interpret())
-} else {
-    fatalError("Error: no input!")
+    print("")
 }
-
diff --git a/Interpreter/Interpreter.swift b/Interpreter/Interpreter.swift
index ce00115..f4a3166 100644
--- a/Interpreter/Interpreter.swift
+++ b/Interpreter/Interpreter.swift
@@ -105,8 +105,8 @@ class Interpreter {
     */
     public func interpret() -> Int {
         let tree = self.parser.parse()
-        let rpn = RPN(tree)
-        rpn.print()
+        //let rpn = RPN(tree)
+        //rpn.print()
         return self.eval(tree)
     }