#include<iostream>
#include<cstdio>
#include<algorithm>
#define mysister
#define maxn 1501
using namespace std;
int cnt=0,n,w,ans=0,fa[maxn];
int find(int u)
{
	return u==fa[u]?u:fa[u]=find(fa[u]);
}
struct bian
{
	int from,to,dist;
	bool operator < (bian a)const
	{
		return dist<a.dist;
	}
}b[maxn*maxn];
int main()
{
	freopen("wire.in","r",stdin);
	freopen("wire.out","w",stdout);
	scanf("%d",&n);
	for(int i=1;i<=n;i++)
	  for(int j=1;j<=n;j++)
	  {
	  	scanf("%d",&w);
	  	if(i<j)
		{
		  b[cnt].from=i;
		  b[cnt].to=j;
		  b[cnt].dist=w;
		  cnt++;
		}
	  }
	sort(b,b+cnt);
	for(int i=1;i<=n;i++)fa[i]=i;
	for(int i=0;i<cnt;i++)
	{
	  if(find(b[i].from)!=find(b[i].to))
	  {
		fa[find(b[i].from)]=find(b[i].to);
		ans+=b[i].dist;
	  }
	}
	printf("%d",ans);
	return 0;
}