# UnionFind 参考は以下のサイト # https://note.nkmk.me/python-union-find/ from collections import defaultdict import heapq class UnionFind(): def __init__(self, n): self.n = n self.parents = [-1] * n def find(self, x): if self.parents[x] < 0: return x else: self.parents[x] = self.find(self.parents[x]) return self.parents[x] def union(self, x, y): x = self.find(x) y = self.find(y) if x == y: return if self.parents[x] > self.parents[y]: x, y = y, x self.parents[x] += self.parents[y] self.parents[y] = x def size(self, x): return -self.parents[self.find(x)] def same(self, x, y): return self.find(x) == self.find(y) def members(self, x): root = self.find(x) return [i for i in range(self.n) if self.find(i) == root] def roots(self): return [i for i, x in enumerate(self.parents) if x < 0] def group_count(self): return len(self.roots()) def all_group_members(self): group_members = defaultdict(list) for member in range(self.n): group_members[self.find(member)].append(member) return group_members def __str__(self): return '\n'.join(f'{r}: {m}' for r, m in self.all_group_members().items()) N,M = map(int, input().split()) ABW = [list(map(int, input().split())) for _ in range(M)] H = [] for a,b,w in ABW: heapq.heappush(H,(w,a,b)) uf = UnionFind(N) ans = 0 while H: w,a,b = heapq.heappop(H) a-=1 b-=1 if not uf.same(a,b): ans += uf.size(a)*uf.size(b)*w uf.union(a,b) print(ans)