#include <cstdio>
using namespace std;
int s1[55][55],s2[55][55],m[55][55];
int main()
{
    int n,i,j,x,smax=-19600,sum,k;
    scanf("%d",&n);
    for(i=1; i<=n; ++i)
        for(j=1; j<=n; ++j)
        {
            scanf("%d",&m[i][j]);
            s1[i][j]=s1[i][j-1]+m[i][j];
            s2[i][j]=s2[i-1][j]+m[i][j];
        }
    for(k=1; k<=n; ++k)
        for(i=1; i<=n-k+1; ++i)
            for(j=1; j<=n-k+1; ++j)
            {
                if (k>=2)
                {
                    sum=0;
                    sum+=s1[i][j+k-1]-s1[i][j-1];
                    sum+=s1[i+k-1][j+k-1]-s1[i+k-1][j-1];
                    sum+=s2[i+k-1][j]-s2[i-1][j];
                    sum+=s2[i+k-1][j+k-1]-s2[i-1][j+k-1];
                    sum-=m[i][j]+m[i+k-1][j]+m[i][j+k-1]+m[i+k-1][j+k-1];
                    if (sum>smax)
                        smax=sum;
                }
                else
                    if (k==1)
                    {
                        if (m[i][j]>smax)
                            smax=m[i][j];
                    }
            }
    printf("%d\n",smax);
    return 0;
}