class UnionFind:
    def __init__(self, size):
        self.parent = list(range(size + 1))  # 1-based indexing
        self.size = [1] * (size + 1)
    
    def find(self, x):
        while self.parent[x] != x:
            self.parent[x] = self.parent[self.parent[x]]  # Path compression
            x = self.parent[x]
        return x
    
    def union(self, x, y):
        fx = self.find(x)
        fy = self.find(y)
        if fx == fy:
            return False
        # Union by size: attach smaller tree to larger tree
        if self.size[fx] < self.size[fy]:
            fx, fy = fy, fx
        self.parent[fy] = fx
        self.size[fx] += self.size[fy]
        return True

def main():
    import sys
    input = sys.stdin.read().split()
    ptr = 0
    N = int(input[ptr])
    ptr += 1
    M = int(input[ptr])
    ptr += 1
    edges = []
    for _ in range(M):
        a = int(input[ptr])
        ptr += 1
        b = int(input[ptr])
        ptr += 1
        w = int(input[ptr])
        ptr += 1
        edges.append((w, a, b))
    edges.sort()
    uf = UnionFind(N)
    total = 0
    for w, a, b in edges:
        fa = uf.find(a)
        fb = uf.find(b)
        if fa != fb:
            total += w * uf.size[fa] * uf.size[fb]
            uf.union(a, b)
    print(total)

if __name__ == "__main__":
    main()