#include <cstdio>

 #include <cstdlib>

 #include <algorithm>

 #include <cmath>

 using namespace std;

 #define  MAXN 10005

 int fa[MAXN];

 struct node

 {

     int from, to, len;

 }arr[MAXN];

 bool cmp(node a, node b)

 {

     return a.len < b.len;

 }

 int m;

 int find(int x)

 {

     if (x == fa[x])

         return x;

     else

         return fa[x] = find(fa[x]);

 }

 int main()

 {

     int n;

     while (scanf("%d",&n)&&n)

     {

         for (int i = ; i <= n; i++)

             fa[i] = i;

         m = ;

         int s = n*(n - ) / ;

         for (int i = ; i < s; i++)

         {

             int a, b, c, d;

             scanf("%d%d%d%d", &a, &b, &c, &d);

             if (d)

             {

                 int x = find(a);

                 int y = find(b);

                 if (x != y)

                     fa[y] = x;

             }

             else

             {

                 arr[m].from = a;

                 arr[m].to = b;

                 arr[m].len = c;

                 m++;

             }

         }

         sort(arr, arr + m, cmp);

         int ans = ;

         for (int i = ; i < m; i++)

         {

             int a = find(arr[i].from);

             int b = find(arr[i].to);

             if (a != b)

             {

                 ans += arr[i].len;

                 fa[b] = a;

             }

         }

         printf("%d\n", ans);

     }

     //system("pause");

     return ;

 }