#include <bits/stdc++.h>
using namespace std;
const long long MOD = 1000000007;
int main(){
  int N;
  cin >> N;
  vector<vector<pair<long long, int>>> E(N);
  for (int i = 0; i < N - 1; i++){
    int u, v, w;
    cin >> u >> v >> w;
    u--;
    v--;
    E[u].push_back(make_pair(w, v));
    E[v].push_back(make_pair(w, u));
  }
  vector<int> p(N, -1);
  vector<vector<pair<long long, int>>> c(N);
  queue<int> Q;
  Q.push(0);
  vector<int> b;
  while (!Q.empty()){
    int v = Q.front();
    Q.pop();
    b.push_back(v);
    for (auto P : E[v]){
      int w = P.second;
      if (w != p[v]){
        p[w] = v;
        c[v].push_back(P);
        Q.push(w);
      }
    }
  }
  reverse(b.begin(), b.end());
  vector<long long> dp1(N, 1);
  vector<long long> dp2(N, 0);
  vector<long long> dp3(N, 0);
  long long ans = 0;
  for (int v : b){
    vector<tuple<long long, long long, long long>> T;
    for (auto P : c[v]){
      int w = P.second;
      long long A = dp1[w];
      long long B = (dp2[w] + dp1[w] * P.first) % MOD;
      long long C = (dp3[w] + dp2[w] * P.first * 2 + dp1[w] * P.first % MOD * P.first) % MOD;
      T.push_back(make_tuple(A, B, C));
      dp1[v] += A;
      dp1[v] %= MOD;
      dp2[v] += B;
      dp2[v] %= MOD;
      dp3[v] += C;
      dp3[v] %= MOD;
    }
    ans += dp3[v];
    int cnt = T.size();
    long long Asum = 0, Bsum = 0, Csum = 0;
    for (int i = 0; i < cnt; i++){
      ans += get<0>(T[i]) * Csum % MOD;
      ans += get<1>(T[i]) * Bsum * 2 % MOD;
      ans += get<2>(T[i]) * Asum % MOD;
      ans %= MOD;
      Asum += get<0>(T[i]);
      Asum %= MOD;
      Bsum += get<1>(T[i]);
      Bsum %= MOD;
      Csum += get<2>(T[i]);
      Csum %= MOD;
    }
  }
  ans %= MOD;
  cout << ans << endl;
}