MOD = 10 ** 9 + 7 class UnionFind: def __init__(self, n): self.n = n self.parents = [-1] * n self.group = 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 self.group -= 1 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 self.group def all_group_members(self): dic = {r:[] for r in self.roots()} for i in range(self.n): dic[self.find(i)].append(i) return dic def __str__(self): return '\n'.join('{}: {}'.format(r, self.members(r)) for r in self.roots()) n, m, X = map(int, input().split()) UF = UnionFind(n) edges = [[] for _ in range(n)] for _ in range(m): x, y, z = map(int, input().split()) x -= 1 y -= 1 if not UF.same(x, y): UF.union(x, y) edges[x].append((y, z)) edges[y].append((x, z)) ans = 0 route = [0] stack = [0] used = [False] * n used[0] = True while stack: pos = stack.pop() for npos, _ in edges[pos]: if used[npos]: continue used[npos] = True stack.append(npos) route.append(npos) size = [1] * n used = [False] * n for pos in route[::-1]: used[pos] = True for npos, z in edges[pos]: if not used[npos]: continue ans += pow(X, z, MOD) * size[npos] * (n - size[npos]) ans %= MOD size[pos] += size[npos] print(ans)