#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
int par[200010],sz[200010];
void init(int n){
	for(int i=0;i<n;i++){
		par[i] = i; sz[i] = 1;
	}
}

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);
}

typedef long long ll;
ll mod = 1000000007;
ll pw(ll a,ll x){
    ll ret = 1;
    while(x){
        if(x&1) (ret *= a) %= mod;
        (a *= a) %= mod; x /= 2;
    }
    return ret;
}

pair<int,pair<int,int>> p[200010];
vector<pair<int,int>> G[200010];
int sum[200010] = {};
void dfs(int s,int p){
    for(auto v:G[s]){
        if(v.first==p) continue;
        dfs(v.first,s);
        sum[s] += sum[v.first];
    }
    sum[s]++;
}

int main(){
    int i,n,m,x; cin >> n >> m >> x;
    for(i=0;i<m;i++){
        int a,b,c; cin >> a >> b >> c; a--; b--;
        p[i] = {c,{a,b}};
    }
    sort(p,p + m);
    ll ans = 0;
    init(n);
    for(i=0;i<m;i++){
        int u = p[i].second.first,v = p[i].second.second;
        if(same(u,v)) continue;
        unite(u,v);
        G[u].push_back({v,p[i].first}); G[v].push_back({u,p[i].first});
    }
    dfs(0,-1);
    for(i=0;i<n;i++){
        for(auto q:G[i]){
            int u = i,v = q.first;
            if(sum[u]<sum[v]) continue;
            (ans += pw(x,q.second)*sum[v]%mod*(n - sum[v])%mod) %= mod;
        }
    }
    cout << ans << endl;
}