#include<stdio.h>
#include<algorithm>
using namespace std;
int a[51][51],maxim=-110,suma=0,jp,capatj,capati;
void calculate(int i, int j, int k)
{
    jp=j;suma=0;
    capatj=j+k-1;
    capati=i+k-1;
    for(;j<=capatj;j++)suma=suma+a[i][j]+a[capati][j];
    for(i=i+1;i<=capati-1;i++)suma=suma+a[i][jp]+a[i][capatj];
    maxim=max(suma,maxim);
}
int main()
{
    /*freopen("date.in","r",stdin);
    freopen("date.out","w",stdout);*/

    int n,i,j,k,l;
    scanf("%d",&n);
    for(i=1;i<=n;i++)
        for(j=1;j<=n;j++)
          {
              scanf("%d",&a[i][j]);
              maxim=max(a[i][j],maxim);
          }

    if(n<=2){printf("%d",maxim);return 0;}
        else maxim=-110;

    k=n-1;
    for(l=1;l<=k;l++)
        for(i=1;i+l-1<=n;i++)
            for(j=1;j+l-1<=n;j++)
                calculate(i,j,k);

    printf("%d",maxim);
    return 0;

}