#include <cstdio>

const int Q=55,INF=1999999999;

int spl[Q][Q],spc[Q][Q];

int main()
{
    //freopen("data.in","r",stdin);
    //freopen("data.out","w",stdout);

    int n,x;

    scanf("%d",&n);
    int max=-INF;
    for(int i=1; i<=n; i++)
    {
        for(int j=1; j<=n; j++)
        {
            scanf("%d",&x);
            if(x>max)
                max=x;
            spl[i][j]=spl[i][j-1]+x;
            spc[i][j]=spc[i-1][j]+x;
        }
    }


    int g;
    for(int k=2; k<=n; k++)
    {
        for(int i=1; i<=n-k+1; i++)
        {
            for(int j=1; j<=n-k+1; j++)
            {
                g=spc[i+k-1][j]-spc[i-1][j] +spc[i+k-1][j+k-1]- spc[i-1][j+k-1] +spl[i][j+k-2]-spl[i][j]+ spl[i+k-1][j+k-2]-spl[i+k-1][j];
                if(g>max )
                    max=g;
            }
        }
    }
    printf("%d",max);
    return 0;
}