#include<cstdio>

 #include<cstring>

 #include<algorithm>

 #include<queue>

 #include<vector>

 #include<set>

 #define CLR(a,b) memset((a),(b),sizeof((a)))

 using namespace std;

 const int inf = 0x3f3f3f3f;

 const int N = ;

 int low[N], s[N];

 int n, ans, num;

 struct Edge{

     int v,c;

     Edge(int _v=,int _c=):v(_v),c(_c){}

     bool operator < (const Edge&r)const{

         return r.c < c;

     }

 };

 vector<Edge>g[N];

 int prim_heap(){

     priority_queue<Edge>q;

     int i, u, v, w;

     Edge p;

     ans = ;//最小生成树总权值

     num = ;//已加入最小生成树的顶点数目

     q.push(Edge(, ));

     while(!q.empty() && num < n){

         p = q.top(); q.pop();

         u = p.v;

         if(s[u]) continue;

         s[u] = ;

         ans += p.c;

         num++;

         for(i = ; i < g[u].size(); ++i){

             v = g[u][i].v;

             if(s[v] == ){

                 w = g[u][i].c;

                 if(w < low[v]){

                     low[v] = w;

                     q.push(Edge(v, w));

                 }

             }

         }

     }

     if(num < n)

         return -;

     return ans;

 }

 int main(){

     int i, j, x;

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

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

             g[i].clear();

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

             for(j = ; j < n; ++j){

                 scanf("%d", &x);

                 g[i].push_back(Edge(j, x));

         }

         CLR(s, ); CLR(low, inf);

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

     }

     return ;

 }