import sys
input = sys.stdin.buffer.readline
sys.setrecursionlimit(10 ** 7)
mod = 10 ** 9 + 7


class UF_tree:
    def __init__(self, n):
        self.root = [-1] * (n + 1)
        self.rank = [0] * (n + 1)

    def find(self, x):
        if self.root[x] < 0:
            return x
        self.root[x] = self.find(self.root[x])
        return self.root[x]

    def isSame(self, x, y):
        return self.find(x) == self.find(y)

    def unite(self, x, y):
        x = self.find(x)
        y = self.find(y)
        if x == y:
            return False
        if self.rank[x] < self.rank[y]:
            self.root[y] += self.root[x]
            self.root[x] = y
        else:
            self.root[x] += self.root[y]
            self.root[y] = x
            if self.rank[x] == self.rank[y]:
                self.rank[x] += 1
        return True

    def size(self, x):
        return -self.root[self.find(x)]


N, M, X = map(int, input().split())
uf = UF_tree(N)
G = [[] for _ in range(N)]
for _ in range(M):
    a, b, c = map(int, input().split())
    a -= 1
    b -= 1
    if uf.unite(a, b):
        G[a].append((b, c))
        G[b].append((a, c))

topo = []
par = [-1] * N
que = [0]
while que:
    s = que.pop()
    topo.append(s)
    for t, k in G[s]:
        if par[t] != -1:
            continue
        par[t] = (s, k)
        que.append(t)
topo.reverse()

ans = 0
size = [1] * N
for s in topo[:-1]:
    p, k = par[s]
    ans += size[s] * (N - size[s]) * pow(X, k, mod) % mod
    ans %= mod
    size[p] += size[s]

print(ans)