#include "bits/stdc++.h"
using namespace std;

class UnionFind {
private:
	vector<int> Rank, Vol, Root;
public:
	UnionFind(int N) : Rank(N, 1), Vol(N, 1), Root(N) {
		for (int i = 0; i < N; i++) Root[i] = i;
	}
	int Find(int N) { return (N == Root[N] ? N : Root[N] = Find(Root[N])); }
	bool Same(int X, int Y) { return Find(X) == Find(Y); }
	void Union(int X, int Y) {
		X = Find(X), Y = Find(Y);
		if (X == Y) return;
		if (Rank[X] > Rank[Y]) Root[X] = Y, Vol[Y] += Vol[X];
		else if (Rank[X] < Rank[Y]) Root[Y] = X, Vol[X] += Vol[Y];
		else Root[Y] = X, Vol[X] += Vol[Y], Rank[X]++;
	}
	int Size(int N) { return Vol[Find(N)]; }
};

constexpr long long MOD = 1000000007;

long long Pow(long long A, long long B) {
	if (B == 0) return 1;
	if (B % 2 == 0) {
		long long C = Pow(A, B / 2);
		return (C * C) % MOD;
	}
	return (A * Pow(A, B - 1)) % MOD;
}

vector<pair<int, int> > Par;
vector<vector<pair<int, int> > > V;
vector<long long> Size;

void DFS(int P) {
	Size[P] = 1;
	for (pair<int, int> NP : V[P]) {
		if (Par[NP.first].first == -2) {
			Par[NP.first] = { P, NP.second };
			DFS(NP.first);
			Size[P] += Size[NP.first];
		}
	}
}

int main() {
	long long N, M;
	long long X;
	cin >> N >> M >> X;
	UnionFind UF(N);
	V.resize(N);
	for (int i = 0; i < M; i++) {
		int S, T;
		long long Z;
		cin >> S >> T >> Z;
		S--, T--;
		if (!UF.Same(S, T)) {
			V[S].push_back({ T, Z });
			V[T].push_back({ S, Z });
			UF.Union(S, T);
		}
	}
	Size.resize(N);
	Par.assign(N, { -2, -1 });
	Par[0] = { -1, 0 };
	DFS(0);
	long long ANS = 0;
	for (int i = 1; i < N; i++) {
		ANS += (Pow(X, Par[i].second) * ((Size[i] * (N - Size[i])) % MOD)) % MOD;
		ANS %= MOD;
	}
	cout << ANS << endl;
}