210305_BOJ_1647.py

import sys
input = sys.stdin.readline


def find_parent(x):
    if parent[x] != x:
        parent[x] = find_parent(parent[x])
    return parent[x]


def union_parent(a, b):
    a = find_parent(a)
    b = find_parent(b)

    if a < b:
        parent[b] = a
    else:
        parent[a] = b


n, m = map(int, input().split())
parent = [i for i in range(n + 1)]

edges = []
result = []

for _ in range(m):
    a, b, c = map(int, input().split())
    edges.append((c, a, b))

edges.sort()

for edge in edges:
    cost, a, b = edge

    if find_parent(a) != find_parent(b):
        union_parent(a, b)
        result.append(cost)

# 마을 분할을 위해 가장 큰 유지비가 드는 간선 제외
print(sum(result[:-1]))