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

#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 FORR2(x,y,arr) for(auto& [x,y]:arr)
#define ALL(a) (a.begin()),(a.end())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
template<class T> bool chmax(T &a, const T &b) { if(a<b){a=b;return 1;}return 0;}
template<class T> bool chmin(T &a, const T &b) { if(a>b){a=b;return 1;}return 0;}
//-------------------------------------------------------


int N;
vector<pair<int,int>> E[202020];
const ll mo=1000000007;
ll ret;

vector<ll> dfs(int cur,int pre) {
	vector<ll> p={1,0,0};
	int pw=0;
	FORR2(e,w,E[cur]) {
		if(e==pre) {
			pw=w;
		}
		else {
			vector<ll> q=dfs(e,cur);
			(ret+=p[0]*q[2]+p[2]*q[0]+2*p[1]*q[1])%=mo;
			(p[0]+=q[0])%=mo;
			(p[1]+=q[1])%=mo;
			(p[2]+=q[2])%=mo;
			
		}
	}
	(p[2]+=p[0]*pw%mo*pw+2*p[1]*pw)%=mo;
	(p[1]+=p[0]*pw)%=mo;
	return p;
}

void solve() {
	int i,j,k,l,r,x,y; string s;
	
	cin>>N;
	FOR(i,N-1) {
		cin>>x>>y>>r;
		E[x-1].push_back({y-1,r});
		E[y-1].push_back({x-1,r});
	}
	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;
}