#include <bits/stdc++.h>
using namespace std;
const long long MOD = 1000000007;
struct unionfind{
	vector<int> p;
	vector<int> sz;
	unionfind(int N): p(vector<int>(N, -1)), sz(vector<int>(N, 1)){
	};
	int root(int x){
		if (p[x] == -1){
			return x;
		} else {
			p[x] = root(p[x]);
			return p[x];
		}
	}
	bool same(int x, int y){
		return root(x) == root(y);
	}
	void unite(int x, int y){
		x = root(x);
		y = root(y);
		if (x != y){
			p[x] = y;
			sz[y] += sz[x];
		}
	}
	int size(int x){
	  return sz[root(x)];
	}
};
long long modpow(long long a, long long b){
	long long ans = 1;
	while (b > 0){
		if (b % 2 == 1){
			ans *= a;
			ans %= MOD;
		}
		a *= a;
		a %= MOD;
		b /= 2;
	}
	return ans;
}
int dfs(vector<vector<int>> &c, vector<int> &dp, int v = 0){
  for (int w : c[v]){
    dp[v] += dfs(c, dp, w);
  }
  return dp[v];
}
int main(){
  int N, M, X;
  cin >> N >> M >> X;
  vector<int> x(M), y(M), z(M);
  for (int i = 0; i < M; i++){
    cin >> x[i] >> y[i] >> z[i];
    x[i]--;
    y[i]--;
  }
  unionfind UF(N);
  vector<vector<pair<long long, int>>> E(N);
  for (int i = 0; i < M; i++){
    if (!UF.same(x[i], y[i])){
      UF.unite(x[i], y[i]);
      long long c = modpow(X, z[i]);
      E[x[i]].push_back(make_pair(c, y[i]));
      E[y[i]].push_back(make_pair(c, x[i]));
    }
  }
  vector<int> p(N, -1);
  vector<long long> d(N, 0);
  vector<vector<int>> c(N);
  queue<int> Q;
  Q.push(0);
  while (!Q.empty()){
    int v = Q.front();
    Q.pop();
    for (auto P : E[v]){
      int w = P.second;
      if (w != p[v]){
        p[w] = v;
        d[w] = P.first;
        c[v].push_back(w);
        Q.push(w);
      }
    }
  }
  vector<int> dp(N, 1);
  dfs(c, dp);
  long long ans = 0;
  for (int i = 1; i < N; i++){
    ans += d[i] * dp[i] % MOD * (N - dp[i]) % MOD;
    ans %= MOD;
  }
  cout << ans << endl;
}