#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#include <time.h>
#include <stack>
#include <array>
#define popcount __builtin_popcount
#define popcountll __builtin_popcountll
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;
struct unionfind{
    vector<int> par, sz;
    unionfind() {}
    unionfind(int n):par(n), sz(n, 1){
        for(int i=0; i<n; i++) par[i]=i;
    }
    int find(int x){
        if(par[x]==x) return x;
        return par[x]=find(par[x]);
    }
    void unite(int x, int y){
        x=find(x); y=find(y);
        if(x==y) return;
        if(sz[x]>sz[y]) swap(x, y);
        par[x]=y;
        sz[y]+=sz[x];
    }
    bool same(int x, int y){
        return find(x)==find(y);
    }
    int size(int x){
        return sz[find(x)];
    }
};
const ll MOD=1e9+7;
ll powmod(ll a, ll k){
    ll ap=a, ans=1;
    while(k){
        if(k&1){
            ans*=ap;
            ans%=MOD;
        }
        ap=ap*ap;
        ap%=MOD;
        k>>=1;
    }
    return ans;
}
int main()
{
	int n, m; ll X;
	cin>>n>>m>>X;
	vector<P> g[200020];
	unionfind uf(n);
	for(int i=0; i<m; i++){
		int a, b, c;
		cin>>a>>b>>c;
		a--; b--;
		if(uf.same(a, b)) continue;
		uf.unite(a, b);
		g[a].push_back({b, c});
		g[b].push_back({a, c});
	}
	ll ans=0;
	int cnt[200020];
	auto dfs=[&](auto dfs, int x, int p)->void{
		cnt[x]=1;
		for(auto q:g[x]){
			int y=q.first;
			if(y==p) continue;
			dfs(dfs, y, x);
			(ans+=(ll)cnt[y]*(n-cnt[y])%MOD*powmod(X, q.second))%=MOD;
			cnt[x]+=cnt[y];
		}
	};
	dfs(dfs, 0, -1);
	cout<<ans<<endl;
	return 0;
}