#include <iostream>
#include <vector>
#include <cmath>
#include <map>
#include <set>
#include <iomanip>
#include <queue>
#include <algorithm>
#include <numeric>
#include <deque>

using namespace std;
 
struct UnionFind {
    vector<long long> par;
    vector<long long> siz;
 
    UnionFind(long long N) : par(N), siz(N) {
        for(long long i = 0; i < N; i++){
            par[i] = i;
            siz[i] = 1;
        }
    }
 
    long long root(long long x) {
        if (par[x] == x) return x;
        return par[x] = root(par[x]);
    }
 
    void unite(long long x, long long y) {
        long long rx = root(x);
        long long ry = root(y);
        if (rx == ry) return;
        par[rx] = ry;
        siz[ry] += siz[rx];
    }
 
    bool same(long long x, long long y) {
        long long rx = root(x);
        long long ry = root(y);
        return rx == ry;
    }
 
    long long size(long long x){
        return siz[root(x)];
    }
};

vector<long long> subtree;

long long subtree_size(long long from, long long p, vector<vector<pair<long long, long long>>> &E){
    long long cnt = 1;

    for (auto [to, C] : E[from]){
        if (to == p) continue;
        cnt += subtree_size(to, from, E);
    }

    return subtree[from] = cnt;
}

const long long m = 1e9+7;

long long mod_exp(long long b, long long e){
    if (e > 0 && b == 0) return 0;
    long long ans = 1;
    b %= m;

    while (e > 0){
        if ((e & 1LL)) ans = (ans * b) % m;
        e = e >> 1LL;
        b = (b*b) % m;
    }

    return ans;
}

long long ans=0, N, X;

void solve(long long from, long long p, vector<vector<pair<long long, long long>>> &E){

    for (auto [to, C] : E[from]){
        if (to == p) continue;
        ans += ((subtree[to]*(N-subtree[to]))%m * mod_exp(X, C)) % m;
        ans %= m;
        solve(to, from, E);
    }
}

template<typename T> using pq = priority_queue<T, vector<T>, greater<T>>;
 
int main(){
 
    long long M, x, y, c;
    cin >> N >> M >> X;
    pq<tuple<long long, long long, long long>> que;
    UnionFind tree(N);
    vector<vector<pair<long long, long long>>> E(N);
 
    for (int i=0; i<M; i++){
        cin >> x >> y >> c;
        x--; y--;
        que.push({c, x, y});
    }
 
    while(!que.empty()){
        tie(c, x, y) = que.top();
        que.pop();
        if (!tree.same(x, y)){
            tree.unite(x, y);
            E[x].push_back({y, c});
            E[y].push_back({x, c});
        }
    }

    subtree.resize(N);
    subtree_size(0, -1, E);
    solve(0, -1, E);
    cout << ans << endl;

    return 0;
}