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)

import sys
input = sys.stdin.readline
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
# def dfs(v,p):
#   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
def dfs(start):
  global ans
  stack = [start]
  visited = [False]*N
  visited[start] = True
  vnum = [0]*N
  while stack:
    v = stack[-1]
    marker = 0
    for u,z,num in edge[v]:
      if visited[u]==False: #前半
        marker = 1
        visited[u]=True
        stack.append(u)
      elif vnum[u]>0: #後半
        ans += vnum[u]*(N-vnum[u])*pow(X,z,mod)
      ans %= mod
      vnum[v] += vnum[u]
    if marker==0: #後半だったら
      vnum[v] += 1
      stack.pop()
  return

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

print(ans)