#include <iostream>
#include <vector>
using namespace std;
using LL = long long;
using ULL = unsigned long long;
#define rep(i,n) for(int i=0; i<(n); i++)

struct dsu{
	struct Node{ int v, z; };
	vector<Node> V;
	dsu(int N){ V.resize(N); rep(i, N) V[i] = { i, 1 }; }
	int root(int a){
		if (V[a].v == a) return a;
		return V[a].v = root(V[a].v);
	}
	int size(int a){ return V[root(a)].z; }
	void unite(int a, int b){
		a = root(a); b = root(b);
		V[a].z += V[b].z;
		V[b].v = a;
	}
};

const ULL M = 1000000007;

ULL powm(ULL a, ULL i){
	if (i == 0) return 1;
	ULL res = powm(a * a % M, i / 2);
	if (i % 2 == 1) res = res * a % M;
	return res;
}

int N, nE;
ULL X;
vector<pair<int, ULL>> E[200000];
ULL Z[200000];
ULL ans = 0;

void dfs(int p, int pre = -1){
	Z[p] = 1;
	for (auto e : E[p]){
		if (e.first == pre) continue;
		dfs(e.first, p);
		Z[p] += Z[e.first];
		ULL tmp = e.second;
		tmp = tmp * Z[e.first] % M * (N - Z[e.first]) % M;
		ans += tmp;
		ans %= M;
	}
}

int main(){
	cin >> N >> nE;
	cin >> X;
	dsu G(N);

	rep(i, nE){
		int u, v; ULL z; cin >> u >> v >> z; u--; v--;
		if (G.root(u) == G.root(v)) continue;
		z = powm(X, z);
		E[u].push_back({ v, z });
		E[v].push_back({ u, z });
		G.unite(u, v);
	}
	dfs(0);

	cout << ans << endl;

	return 0;
}