#include <bits/stdc++.h>
using namespace std;

long long N; 
vector<vector<pair<int,long long>>> edge;
vector<long long> dist;

void dfs(int from, int prev = -1){
	for(int i = 0; i < edge[from].size(); ++i){
		int to = edge[from][i].first;
		if(to==prev) continue;
		dist[to] = dist[from] + edge[from][i].second;
		dfs(to,from);
	}
}

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	cin >> N;
	edge.resize(N);
	dist.resize(N);

	for(int i = 0; i < N-1; ++i){
		int u,v;
		long long w;
		cin >> u >> v >> w;
		u--,v--;
		edge[u].push_back({v,w});
		edge[v].push_back({u,w});
	}
	long long ans = 0;
	for(int i = 0; i < N; ++i){
		for(int j = 0; j < N; ++j) dist[j] = 0;
		dfs(i,-1);
		ans += accumulate(dist.begin(),dist.end(),0LL);
	}
	cout << ans << endl;
    return 0;
}