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)

  def roots(self):
    return [i for i, x in enumerate(self.parents) if x < 0]

  def num_roots(self):
    return len([i for i, x in enumerate(self.parents) if x < 0])

  def members(self, x):
    root = self.find(x)
    return [i for i in range(self.n) if self.find(i) == root]

  def num_members(self,x):
    return abs(self.parents[self.find(x)])

  def __str__(self):
    return '\n'.join('{}: {}'.format(r, self.members(r)) for r in self.roots())


import sys
sys.setrecursionlimit(10**6)
input = sys.stdin.readline

def dfs(v,p):
  ans = 0
  for unum in edge[v]:
    u,num = divmod(unum,mod2)
    if u!=p:
      v_num = dfs(u,v)
      e_cnt[num] = v_num*(N-v_num)
      ans += v_num
  return ans+1

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)]
e_length = [0]*(N-1)
num = 0
mod2 = 10**6
for x,y,z in A:
  x -= 1
  y -= 1
  if not uf.same(x,y):
    uf.union(x,y)
    e_length[num] = z
    edge[x].append(y*mod2+num)
    edge[y].append(x*mod2+num)
    num += 1
    if num==N-1:
      break
e_cnt = [0]*(N-1)
used = [False]*(N-1)
dfs(0,-1)

mod = 10**9+7
ans = 0
for i in range(N-1):
  ans += e_cnt[i]*pow(X,e_length[i],mod)
  ans %= mod
print(ans)