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

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

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

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

    def group_count(self):
        return len(self.roots())

    def all_group_members(self):
        return {r: self.members(r) for r in self.roots()}

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

def dfs_size(x):
    sizex = 1
    for y in Tree[x]:
        if y != parent[x]:
            parent[y] = x
            sizex += dfs_size(y)
    size[x] = sizex
    return sizex

import sys
sys.setrecursionlimit(1<<30)
mod = 10**9+7
N,M,X = map(int,input().split())
Tree = [[] for _ in range(N)]
edges = []
uf = UnionFind(N)
for i in range(M):
    x,y,z = map(int,input().split())
    if not uf.same(x-1,y-1):
        uf.union(x-1,y-1)
        Tree[x-1].append(y-1)
        Tree[y-1].append(x-1)
        edges.append((x,y,z))
size = [-1]*N
parent = [-1]*N
dfs_size(0)
ans = 0
for x,y,z in edges:
    s = min(size[x-1],size[y-1])
    ans += s*(N-s)*pow(X,z,mod)
    ans %= mod
print(ans)