class UnionFind:
  def __init__(self, n):
    self.node = [-1 for _ in range(n)]

  def root(self, v):
    if self.node[v] < 0:
      return v

    st = []
    while self.node[v] >= 0:
      st.append(v)
      v = self.node[v]

    for u in st:
      self.node[u] = v

    return v

  def size(self, v):
    v = self.root(v)
    return (- self.node[v])

  def same(self, u, v):
    return self.root(u) == self.root(v)

  def unite(self, u, v):
    ru = self.root(u)
    rv = self.root(v)
    if ru == rv:
      return

    du = self.node[ru]
    dv = self.node[rv]
    if du <= dv:
      self.node[rv] = ru
      self.node[ru] += dv
    else:
      self.node[ru] = rv
      self.node[rv] += du


MOD = 10 ** 9 + 7

n, m, x = map(int, input().split())

g = [[] for _ in range(n)]
edges = []
uf = UnionFind(n)
for _ in range(m):
  xi, yi, zi = map(int, input().split())
  xi -= 1
  yi -= 1
  if not uf.same(xi, yi):
    uf.unite(xi, yi)
    g[xi].append(yi)
    g[yi].append(xi)
    edges.append((xi, yi, zi))

dp = [0 for _ in range(n)]
src = 0
st = [~ src, src]
par = [None for _ in range(n)]
while len(st) > 0:
  cur = st.pop()
  if cur >= 0:
    for nxt in g[cur]:
      if par[cur] == nxt:
        continue
      par[nxt] = cur
      st.append(~ nxt)
      st.append(nxt)
  else:
    dp[~ cur] += 1
    if not par[~ cur] is None:
      dp[par[~ cur]] += dp[~ cur]

ans = 0
for xi, yi, zi in edges:
  if par[xi] == yi:
    ans = (ans + dp[xi] * (n - dp[xi]) * pow(x, zi, MOD) % MOD) % MOD
  else:
    ans = (ans + dp[yi] * (n - dp[yi]) * pow(x, zi, MOD) % MOD) % MOD

print(ans)