#include<bits/stdc++.h>
using namespace std;
int Father[5000];
int ans = 0;
struct Node {
	int u, v, e, s;
	bool operator < (const Node &p)const { return s == p.s ? e< p.e : s>p.s; }
}node[5000];
int FindFather(int x) { return Father[x] < 0 ? x : FindFather(Father[x]); }
void Umerge(Node x)
{
	int Fx = FindFather(x.u);
	int Fy = FindFather(x.v);
	if (Fx != Fy)
	{
		Father[Fy] += Father[Fx];
		Father[Fx] = Fy;
		if (x.s == 0)ans += x.e;
	}
}
int main() {
	int  n;
	while (cin >> n)
	{
		if (n == 0)break;
		memset(Father, -1, sizeof(Father));
		int m = n * (n - 1) / 2;
		for (int i = 0; i<m; ++i) cin >> node[i].u >> node[i].v >> node[i].e >> node[i].s;
		sort(node, node + m);
		for (int i = 0; i <m; i++) Umerge(node[i]);
		cout << ans << endl;
	}
}