#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

long long mod = 1000000007;

class UnionFind {
public:
	vector<int> par;

	void init(int sz) {
		par.resize(sz, -1);
	}
	int root(int pos) {
		if (par[pos] == -1) return pos;
		par[pos] = root(par[pos]);
		return par[pos];
	}
	void unite(int u, int v) {
		u = root(u); v = root(v);
		if (u != v) par[u] = v;
	}
	bool same(int u, int v) {
		u = root(u); v = root(v);
		if (u == v) return true;
		return false;
	}
};

long long modpow(long long a, long long b, long long m) {
	long long p = 1, q = a;
	for (int i = 0; i < 62; i++) {
		if ((b / (1LL << i)) % 2LL == 1) {
			p *= q; p %= m;
		}
		q *= q; q %= m;
	}
	return p;
}

// 入力
long long N, M, X;
long long A[1 << 18], B[1 << 18], C[1 << 18];

// 木の情報
UnionFind UF;
vector<int> G[1 << 18];
int dp[1 << 18];
bool used[1 << 18];

void dfs(int pos) {
	dp[pos] = 1;
	for (int i : G[pos]) {
		if (dp[i] >= 1) continue;
		dfs(i);
		dp[pos] += dp[i];
	}
}

int main() {
	// Step #1. 入力
	cin >> N >> M >> X;
	for (int i = 1; i <= M; i++) cin >> A[i] >> B[i] >> C[i];

	// Step #2. UF
	UF.init(N + 2);
	for (int i = 1; i <= M; i++) {
		if (UF.same(A[i], B[i]) == false) {
			UF.unite(A[i], B[i]);
			G[A[i]].push_back(B[i]);
			G[B[i]].push_back(A[i]);
			used[i] = true;
		}
	}

	// Step #3. 答えを求める
	long long Answer = 0;
	dfs(1);
	for (int i = 1; i <= M; i++) {
		if (used[i] == false) continue;
		long long cost = modpow(X, C[i], mod);
		long long t1 = min(dp[A[i]], dp[B[i]]);
		long long t2 = N - t1;
		Answer += (t1 * t2 % mod) * cost % mod;
		Answer %= mod;
	}
	cout << Answer << endl;
	return 0;
}