#include<cstdio>
using namespace std;
int i,j,i1,j1,A[110][110],R[110][110],C[110][110],SOL,sum,n;
int main()
{
    scanf("%d",&n);
    SOL=1<<29;
    SOL-=SOL;
    for(i=1;i<=n;i++)
        for(j=1;j<=n;j++)
        {
            scanf("%d",&A[i][j]);
            if(SOL<A[i][j])SOL=A[i][j];
            R[i][j]=R[i][j-1]+R[i-1][j]-R[i-1][j-1]+A[i][j];
        }

    for(i=1;i<=n;i++)
        for(j=1;j<=n;j++)
            for(int size=1;size<=n;size++)
            {
                if(i+size>n)break;
                if(j+size>n)break;
                sum=R[i+size][j+size]+R[i-1][j-1]-R[i+size][j-1]-R[i-1][j+size]-R[i+size-1][j+size-1]+R[i][j+size-1]+R[i+size-1][j]-R[i][j];
                if(sum>SOL)SOL=sum;
            }
    printf("%d\n",SOL);
    return 0;
}