// https://atcoder.jp/contests/otemae2019/submissions/6651746

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll mod = 1000000007;

int N;
vector<pair<int, int>> G[500000];

ll ans = 0;

int subnum[500000];
int calc_subnum(int v, int from) {
	int ret = 1;
	for (int i = 0; i < G[v].size(); i++){
		int to = G[v][i].second;
		if (to == from)continue;
		ret += calc_subnum(to, v);
	}
	return subnum[v] = ret;
}

//eを通るu-v pathの個数
void calc1(int v, int from, int l) {
	ans += (ll)subnum[v] * (N - subnum[v]) % mod * l % mod * l;
	ans %= mod;
	for (int i = 0; i < G[v].size(); i++) {
		int to = G[v][i].second;
		if (to == from)continue;
		calc1(to, v, G[v][i].first);
	}
}
//根とe'の間にe
ll calc2(int v, int from) {
	ll ret = 0;
	for (int i = 0; i < G[v].size(); i++) {
		int to = G[v][i].second;
		if (to == from)continue;
		ll next = calc2(to, v);
		ans += next * (N - subnum[to]) % mod * G[v][i].first; ans %= mod;
		ret += next; ret += subnum[to] * (ll)G[v][i].first; ret %= mod;
	}
	return ret;
}//eとe'がバラバラ
ll calc3(int v, int from) {
	ll ret = 0;
	vector<ll> x;
	for (int i = 0; i < G[v].size(); i++) {
		int to = G[v][i].second;
		if (to == from)continue;
		ll next = (calc3(to, v) + subnum[to] * (ll)G[v][i].first) % mod;
		x.push_back(next); ret += next; ret %= mod;
	}
	ll sum = 0;
	for (int i = 0; i < x.size(); i++) {
		sum += x[i];
	}
	sum %= mod;
	for (int i = 0; i < x.size(); i++) {
		ans += x[i] * (sum - x[i] + mod); ans %= mod;
	}
	return ret;
}
int main() {
	cin >> N;
	//入力
	for (int i = 0; i < N - 1; i++) {
		int A, B, C; cin >> A >> B >> C; A--; B--;
		G[A].push_back({C, B});
		G[B].push_back({C, A});
	}

	calc_subnum(0, -1);
	calc1(0, -1, 0);
	calc2(0, -1);
	//eとe'の上下を入れ替えてもう一度
	calc2(0, -1);
	calc3(0, -1);

	cout << ans << endl;
	return 0;
}