#include<cstdio>
using namespace std;
int a[52][52];
int main(){
    freopen("MaxSquare.in","r",stdin);
    freopen("MaxSquare.out","w",stdout);
int smax=0,n,i,j,i1,i2,s=0;
scanf("%d",&n);
for(i=1;i<=n;i++)
    for(j=1;j<=n;j++)
        scanf("%d",&a[i][j]);
for(i=1;i<=n;i++){
    for(j=1;j<=n;j++){
            for(i1=1;i1<=n-j+1;i1++){
                for(i2=0;i2<=i+i1-1;i2++){
                    s=s+a[i][j+i2];
                    s=s+a[i+i1-1][j+i2];
                    s=s+a[i+i2][j];
                    s=s+a[i+i2][j+i1-1];
                }
                    s=s-a[i][j];
                    s=s-a[i][j+i1-1];
                    s=s-a[i+i1-1][j];
                    s=s-a[i+i1-1][j+i1-1];
                if(s>smax)
                    smax=s;
                    s=0;
            }
    }
}
printf("%d",smax);
return 0;
}