#include <stdio.h>
#include <string.h>
#define MAX 110
#define INF 100000000
int graph[MAX][MAX] ;
bool visited[MAX] ;
int prim(int n)
{
	int closest[MAX] ;
	int lowcost[MAX] ;
	memset(visited,false,sizeof(visited)) ;
	for(int i = 1 ; i <= n ; ++i)
	{
		closest[i] = 1;
		lowcost[i] = graph[1][i] ;
	}
	visited[1] = true ;
	for(int i = 1 ; i <= n ; ++i)
	{
		int temp = INF ;
		int t = 1 ;
		for(int j = 1 ; j <= n ; ++j)
		{
			if(!visited[j] && temp>lowcost[j])
			{
				temp = lowcost[j] ;
				t = j ;
			}
		}
		if(temp == INF)
		{
			break ;
		}
		visited[t] = true ;
		for(int j = 1 ; j <= n ; ++j)
		{
			if(!visited[j] && lowcost[j]>graph[t][j])
			{
				lowcost[j] = graph[t][j] ;
				closest[j] = t ;
			}
		}
	}
	int sum = 0 ;
	for(int i = 2 ; i <= n ; ++i)
	{
		sum += lowcost[i] ;
	}
	return sum ;
}

int main()
{
	int n = 0 ;
	while(scanf("%d",&n) && n)
	{
		int m = (n*(n-1))/2 ;
		for(int i = 0 ; i <= n ; ++i)
		{
			for(int j = 0 ; j <= i ; ++j)
			{
				graph[i][j] = graph[j][i] = INF ;
			}
		}
		for(int i = 1 ; i <= m ; ++i)
		{
			int x,y,w,flag;
			scanf("%d%d%d%d",&x,&y,&w,&flag);
			if(flag)
			{
				graph[x][y] = graph[y][x] = 0;
			}
			else
			{
				graph[x][y] = graph[y][x] = w ;
			}
		}
		int ans = prim(n);
		printf("%d\n",ans) ;
	}
	return 0 ;
}