import sys
sys.setrecursionlimit(10**7)
input = sys.stdin.readline
class UnionFind():
    def __init__(self, n):
        self.n = n
        self.parents = [-1] * (n+1)

    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)



mod = 10 ** 9 + 7
from collections import deque

def main():
    N, M, X = map(int, input().split())
    Uni = UnionFind(N)
    res = 0
    que = []
    G = [[] for i in range(N+1)]
    for i in range(M):
        x, y, z = map(int, input().split())
        if Uni.same(x, y) == True:
            continue
        else:
            Uni.union(x, y)
            G[x].append(y)
            G[y].append(x)
            que.append((x, y, z))

    #ここで得られる構造は木構造
    visited = [False for i in range(N+1)]
    depth = [0 for i in range(N+1)]
    child_cnt = [1 for i in range(N+1)]

    stack = deque([])
    def dfs(s_node):
        visited[s_node] = True
        for node in G[s_node]:
            if visited[node] == False:
                depth[node] = depth[s_node] + 1
                dfs(node)
        stack.append(s_node)  


    dfs(1)
    while stack:
        s_node = stack.popleft()
        for node in G[s_node]:
            if depth[node] > depth[s_node]:
                child_cnt[s_node] += child_cnt[node]    
    for x, y, z in que:
        if depth[x] > depth[y]:
            res += pow(X, z, mod) * child_cnt[x]*(N-child_cnt[x])
            res %= mod
        else:
            res += pow(X, z, mod) * child_cnt[y]*(N-child_cnt[y])
            res %= mod
    print(res)
    return


if __name__ == "__main__":
    main()