4 5
1 2 1
1 3 4
2 3 2
2 4 5
3 4 3

6

n, m = map(int, input().split())
edges = [tuple(map(int, input().split())) for _ in range(m)]
edges.sort(key=lambda x: x[2])
parent = list(range(n+1))
def find(x):
    if parent[x] != x:
        parent[x] = find(parent[x])
    return parent[x]
def union(x, y):
    px, py = find(x), find(y)
    if px == py:
        return False
    parent[px] = py
    return True
total = 0
for u, v, w in edges:
    if union(u, v):
        total += w
print(total)