#include<bits/stdc++.h>

 using namespace std;

 const int maxn=;

 const int INF=0x3f3f3f3f;

 inline void read(int &tmp)

 {

     int x=;char c=getchar();

     for(tmp=;!isdigit(c);c=getchar()) if(c=='-') x=-;

     for(;isdigit(c);tmp=tmp*+c-,c=getchar());

     tmp*=x;

 }

 int n,sum,tot,m,mp[maxn][maxn],w[maxn];

 typedef pair<int,int> P;

 priority_queue< P,vector<P>,greater<P> >q;

 bool v[maxn];

 void Prim()

 {

     memset(w,0x3f,sizeof(w));

     w[]=;q.push(make_pair(,));

     while(!q.empty())

     {

         int Top=q.top().second;q.pop();

         if(v[Top]) continue;

         v[Top]=;sum+=w[Top];++tot;

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

             if(mp[Top][i]<w[i]&&mp[Top][i]>&&v[i]==false) {w[i]=mp[Top][i];q.push(make_pair(w[i],i));}

     }

 }

 int main()

 {

     read(n);

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

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

                 {read(mp[i][j]);if(i==j) mp[i][j]=INF;}

     Prim();

     printf("%d",sum);

     return ;

 }