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 same(self, x, y):
    return self.find(x) == self.find(y)

N, M, X = map(int, input().split())
A = [list(map(int, input().split())) for _ in range(M)]
uf = UnionFind(N)
edge = [[] for _ in range(N)]
num = 0
for x,y,z in A:
  x -= 1
  y -= 1
  if not uf.same(x,y):
    uf.union(x,y)
    edge[x].append((y,z,num))
    edge[y].append((x,z,num))
    num += 1
    if num==N-1:
      break

import sys
sys.setrecursionlimit(10**6)

def dfs(v,p):
  global ans
  res = 0
  for u,z,num in edge[v]:
    if u!=p:
      v_num = dfs(u,v)
      ans += v_num*(N-v_num)*pow(X,z,mod)
      ans %= mod
      res += v_num
  return res+1

ans = 0
mod = 10**9+7
dfs(0,-1)

print(ans)