#include<bits/stdc++.h>
using namespace std;
using LL=long long;
using ULL=unsigned long long;
#define rep(i,n) for(int i=0; i<(n); i++)

ULL M = 1000000007;

struct Mat{
  ULL S=0,L=0,C=0;
  Mat add_D0() const { return Mat{S,L,(C+1)%M}; }
  Mat extend(ULL d) const { return Mat{(S+L*2*d%M+d*d%M*C)%M,(L+C*d)%M,C}; }
};

ULL getSqSum(Mat l,Mat r){
  ULL res=0;
  res+= (l.S*r.C%M + l.L*2*r.L%M + r.S*l.C%M)%M;
  return res%M;
}

Mat operator+(Mat l,Mat r){
  return { (l.S+r.S)%M, (l.L+r.L)%M, (l.C+r.C)%M };
}

struct Edge{ int to; ULL d; };

int N;
vector<Edge> E[200000];
Edge P[200000]={};
vector<int> I;
Mat V[200000];
ULL ans=0;

int main(){
  scanf("%d",&N);
  rep(i,N-1){
    int u,v,d; scanf("%d%d%d",&u,&v,&d); u--; v--;
    E[u].push_back({v,d});
    E[v].push_back({u,d});
  }
  int pI=0;
  P[1]={-1,0}; I.push_back(1);
  while(I.size()>pI){
    int p=I[pI++];
    for(Edge e:E[p]) if(P[p].to!=e.to){ P[e.to]={p,e.d}; I.push_back(e.to); }
  }
  reverse(I.begin(),I.end());
  I.pop_back();

  for(int p:I){
    V[p] = V[p].add_D0();
    V[p] = V[p].extend(P[p].d);
    ans += getSqSum(V[P[p].to],V[p]);
    ans += V[p].S;
    V[P[p].to] = V[P[p].to] + V[p];
  }

  printf("%llu\n",ans%M);

  return 0;
}