#include <cstdio>

using namespace std;
int Max,nr,i,j,a[54][54],x[54][54],y[54][54],n,l;
int main()
{
  //  freopen("baa.in","r",stdin);
    //freopen("baa.out","w",stdout);

    scanf("%d",&n);
    Max=-100000000;

    for(i=1;i<=n;++i)
    for(j=1;j<=n;++j)
    {
        scanf("%d",&a[i][j]);
        if(a[i][j]>Max) Max=a[i][j];
    }

    for(i=1;i<=n;++i)
    for(j=1;j<=n;++j)
    x[i][j]=x[i][j-1]+a[i][j];

    for(j=1;j<=n;++j)
    for(i=1;i<=n;++i)
    y[i][j]=y[i-1][j]+a[i][j];

    for(i=1;i<=n;++i)
    for(j=1;j<=n;++j)
    for(l=1;i+l<=n && j+l<=n;++l)
    {
         nr=x[i][j+l]-x[i][j-1];
        nr+=x[i+l][j+l]-x[i+l][j-1];
        nr+=y[i+l][j]-y[i-1][j];
        nr+=y[i+l][j+l]-y[i-1][j+l];
        nr-=a[i][j];
        nr-=a[i+l][j];
        nr-=a[i][j+l];
        nr-=a[i+l][j+l];
        if(nr>Max) Max=nr;
    }

    printf("%d\n",Max);

    return 0;
}