#include <iostream>
#include<fstream>
#include<cmath>
using namespace std;
ifstream f("date.in");
ofstream g("date.out");
short n,i,j,a[51][51],k,p,l;
int s=0;
int maxx=-20000000;
int maxim(int a,int b)
{
	if(a<b)return b;
	else return a;
}
int main() {
	cin>>n;
	//f>>n;
	if(n==1){cin>>k;cout<<k;return 0;}
	for(i=1;i<=n;i++)
		for(j=1;j<=n;j++)
			cin>>a[i][j];
			//f>>a[i][j];
		
		for(i=1;i<=n;i++)
			for(j=1;j<=n;j++)
				for(k=i+1;k<=n;k++)
					for(p=j+1;p<=n;p++)
						if(abs(p-j)==abs(k-i))
						{
							s=0;
							l=abs(p-j)+1;
							//g<<l<<" ";
							for(int i1=1;i1<=l;i1++)
								s+=a[i][j+i1]+a[i+i1][j]+a[i+i1][p]+a[k][j+i1];
							s+=a[i][j]-a[k][p];//+a[k][j]+a[i][p];
							maxx=maxim(maxx,s);	
						}
							
			cout<<maxx;
						//g<<maxx;
	
	return 0;
}