class UnionFind:
    def __init__(self, n):
        self.n = n
        self.parent_or_size = [-1] * n

    def merge(self, a, b):
        x = self.root(a)
        y = self.root(b)
        if x == y:
            return False
        if -self.parent_or_size[x] < -self.parent_or_size[y]:
            x, y = y, x
        self.parent_or_size[x] += self.parent_or_size[y]
        self.parent_or_size[y] = x
        return True

    def same(self, a, b):
        return self.root(a) == self.root(b)

    def root(self, a):
        if self.parent_or_size[a] < 0:
            return a
        self.parent_or_size[a] = self.root(self.parent_or_size[a])
        return self.parent_or_size[a]

    def size(self, a):
        return -self.parent_or_size[self.root(a)]


N, M = map(int, input().split())

uf = UnionFind(N)


def valtotuple(val: int):
    a = val % N
    val //= N
    b = val % N
    c = val // N
    return c, a, b


def tupletoval(tup) -> int:
    c, a, b = tup
    return c * N * N + a * N + b


es = []
for i in range(M):
    a, b, c = map(int, input().split())
    es.append(tupletoval((c, a - 1, b - 1)))

es.sort()
ans = 0
for val in es:
    c, a, b = valtotuple(val)
    if not uf.same(a, b):
        ans += c * uf.size(a) * uf.size(b)
        uf.merge(a, b)

print(ans)