#include <iostream>
#include <algorithm>
#include <iomanip>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <cassert>

#define debug_value(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << #x << "=" << x << endl;
#define debug(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << x << endl;

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

using namespace std;
typedef long long ll;


const ll MOD = 1000000007;

class ModInt{
    public:
    ll v;
    ModInt(ll _v = 0){
        if(_v >= MOD) _v %= MOD;
        v = _v;
    }
    ModInt operator+(ll n){
        return ModInt((v+n)%MOD);
    }
    ModInt operator-(ll n){
        return ModInt((v-n+MOD)%MOD);
    }
    ModInt operator*(ll n){
        if(n >= MOD) n %= MOD;
        return ModInt((v*n)%MOD);
    }
    ModInt operator/(ll n){
        return ModInt((ModInt(n).inv()*v).v%MOD);
    }

    void operator+=(ll n){
        v = (v+n)%MOD;
    }
    void operator-=(ll n){
        v = (v-n+MOD)%MOD;
    }
    void operator*=(ll n){
        v = (v*n)%MOD;
    }
    
    
    ModInt operator+(ModInt n){
        return ModInt((v+n.v)%MOD);
    }
    ModInt operator-(ModInt n){
        return ModInt((v-n.v+MOD)%MOD);
    }
    ModInt operator*(ModInt n){
        return ModInt((v*n.v)%MOD);
    }
    ModInt operator/(ModInt n){
        return ModInt((n.inv()*v).v%MOD);
    }

    void operator+=(ModInt n){
        v = (v+n.v)%MOD;
    }
    void operator-=(ModInt n){
        v = (v-n.v+MOD)%MOD;
    }
    void operator*=(ModInt n){
        v = (v*n.v)%MOD;
    }

    void operator=(ModInt n){
        v = n.v;
    }
    void operator=(ll n){
        v = n;
    }

    ModInt inv(){
        if(v == 1) return ModInt(1);
        else return ModInt(MOD-ModInt(MOD%v).inv().v*(MOD/v)%MOD);
    }
};

ostream& operator<<(ostream& os, const ModInt& m){
    os << m.v;
    return os;
}

istream & operator >> (istream &in,  ModInt &m){
    in >> m.v;
    return in;
}

ModInt dp_sum[200000];
ModInt dp_square[200000];
ModInt cnt_ch[200000];

struct edge{
    int to;
    ModInt cost;
};

int n;
vector<edge> G[200000];
ModInt ans;
bool used[200000];

void dfs(int v){
    used[v] = true;
    vector<edge> visited;
    for(auto e : G[v]){
        if(!used[e.to]){
            visited.push_back(e);
            dfs(e.to);
            cnt_ch[v] += cnt_ch[e.to];
            dp_square[v] += dp_square[e.to]+dp_sum[e.to]*e.cost*2+e.cost*e.cost*cnt_ch[e.to];
            dp_sum[v] += dp_sum[e.to]+e.cost*cnt_ch[e.to];
        }
    }
    for(edge e : visited){
        ModInt x = dp_square[e.to]+dp_sum[e.to]*e.cost*2+e.cost*e.cost*cnt_ch[e.to];
        ans += x*(cnt_ch[v]-cnt_ch[e.to]);
        x = dp_sum[e.to]+e.cost*cnt_ch[e.to];
        ans += x*(dp_sum[v]-x);
    }
    ans += dp_square[v];
    cnt_ch[v]+=1;
    // cout << v << ' ' << dp_sum[v] << ' ' << dp_square[v] << ' ' << ans << ' ' << cnt_ch[v] << endl;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << setprecision(10) << fixed;
    cin >> n;
    for(int i = 0; i < n-1; i++){
        int u, v;
        ModInt w;
        cin >> u >> v >> w;
        u--; v--;
        G[u].push_back((edge){v, w});
        G[v].push_back((edge){u, w});
    }
    dfs(0);
    cout << ans << endl;
}