N, M = map(int, input().split())
ABW = [list(map(int, input().split())) for _ in range(M)]

def root(x):
    if P[x] < 0: return x
    P[x] = root(P[x])  # 経路圧縮
    return P[x]

def unite(x, y):
    x = root(x)
    y = root(y)
    if x == y: return
    if x > y: x, y = y, x
    P[x] += P[y]
    P[y] = x

def same(x, y):
    return root(x) == root(y)

def size(x):
    x = root(x)
    return -P[x]

P = [-1] * (N + 1)
ABW.sort(key=lambda x: x[2])
ans = 0
for a, b, w in ABW:
    if not same(a, b):
        ans += w * size(a) * size(b)
        unite(a, b)
    if size(1) == N:
        print(ans)
        exit()