#include <bits/stdc++.h>
using namespace std;
typedef signed long long ll;

#undef _P
#define _P(...) (void)printf(__VA_ARGS__)
#define FOR(x,to) for(x=0;x<(to);x++)
#define FORR(x,arr) for(auto& x:arr)
#define ITR(x,c) for(__typeof(c.begin()) x=c.begin();x!=c.end();x++)
#define ALL(a) (a.begin()),(a.end())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
//-------------------------------------------------------

const ll mo=1000000007;
ll modpow(ll a, ll n = mo-2) {
	ll r=1;a%=mo;
	while(n) r=r*((n%2)?a:1)%mo,a=a*a%mo,n>>=1;
	return r;
}

template<int um> class UF {
	public:
	vector<int> par,rank,cnt;
	UF() {par=rank=vector<int>(um,0); cnt=vector<int>(um,1); for(int i=0;i<um;i++) par[i]=i;}
	void reinit() {int i; FOR(i,um) rank[i]=0,cnt[i]=1,par[i]=i;}
	int operator[](int x) {return (par[x]==x)?(x):(par[x] = operator[](par[x]));}
	int count(int x) { return cnt[operator[](x)];}
	int operator()(int x,int y) {
		if((x=operator[](x))==(y=operator[](y))) return x;
		cnt[y]=cnt[x]=cnt[x]+cnt[y];
		if(rank[x]>rank[y]) return par[x]=y;
		rank[x]+=rank[x]==rank[y]; return par[y]=x;
	}
};
UF<202020> uf;

int N,M,X;
vector<pair<int,int>> E[202020];

int C[202020];

ll ret;
int dfs(int cur,int pre) {
	C[cur]=1;
	FORR(e,E[cur]) if(e.first!=pre) {
		C[cur]+=dfs(e.first,cur);
	}
	FORR(e,E[cur]) if(e.first==pre) {
		ret+=C[cur]*(N-C[cur])%mo*modpow(X,e.second)%mo;
	}
	return C[cur];
}


void solve() {
	int i,j,k,l,r,x,y; string s;
	
	cin>>N>>M>>X;
	FOR(i,M) {
		cin>>x>>y>>r;
		x--,y--;
		if(uf[x]!=uf[y]) {
			E[x].push_back({y,r});
			E[y].push_back({x,r});
			uf(x,y);
		}
	}
	dfs(0,0);
	cout<<ret<<endl;
}


int main(int argc,char** argv){
	string s;int i;
	if(argc==1) ios::sync_with_stdio(false), cin.tie(0);
	FOR(i,argc-1) s+=argv[i+1],s+='\n'; FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin);
	cout.tie(0); solve(); return 0;
}