class UnionFindVerSize():
    def __init__(self, N):
        self._parent = [n for n in range(0, N)]
        self._size = [1] * N

    def find_root(self, x):
        if self._parent[x] == x: return x
        self._parent[x] = self.find_root(self._parent[x])
        return self._parent[x]

    def unite(self, x, y):
        gx = self.find_root(x)
        gy = self.find_root(y)
        if gx == gy: return

        if self._size[gx] < self._size[gy]:
            self._parent[gx] = gy
            self._size[gy] += self._size[gx]
        else:
            self._parent[gy] = gx
            self._size[gx] += self._size[gy]

    def get_size(self, x):
        return self._size[self.find_root(x)]

    def is_same_group(self, x, y):
        return self.find_root(x) == self.find_root(y)

    def calc_group_num(self):
        N = len(self._parent)
        ans = 0
        for i in range(N):
            if self.find_root(i) == i:
                ans += 1
        return ans

import sys
from collections import deque

input=sys.stdin.readline


N,M,X=map(int,input().split())
uf=UnionFindVerSize(N)
ans=0
mod=10**9+7

MST = []
edge = [[] for i in range(N)]
for i in range(M):
    x,y,z=map(int,input().split())
    x-=1
    y-=1
    if not uf.is_same_group(x,y):
        uf.unite(x,y)
        edge[x].append((y,z))
        edge[y].append((x,z))

deq=deque([0])
ans=[]
used=[False]*N
used[0]=True
while deq:
    v=deq.popleft()
    ans.append(v)
    for nv,c in edge[v]:
        if not used[nv]:
            used[nv]=True
            deq.append(nv)

size=[-1 for i in range(N)]

for v in ans[::-1]:
    size[v]=1
    for nv,c in edge[v]:
        if not size[nv]==-1:
            size[v]+=size[nv]

res=0
for u in range(N):
    for v,c in edge[u]:
        if size[u]<size[v]:
            tmp=pow(X,c,mod)
            tmp*=size[u]
            tmp%=mod
            tmp*=(N-size[u])
            tmp%=mod
            res+=tmp
            res%=mod

print(res)