#include<cstdio>
#include<cstring>
#include<climits>
#include<algorithm>
using namespace std;
int n,i,j,k,v[55][55],rez,m,r,i1,x,y;

int main()
{
    scanf("%d",&n);
    rez=-10000000;
    for (i=1;i<=n;i++)
        for (j=1;j<=n;j++)
            scanf("%d",&v[i][j]),rez=max(rez,v[i][j]);
    for (i=1;i<=n;i++)
        for (j=1;j<=n;j++)
            {
                m=min(n-i,n-j);
                for (k=1;k<=m;k++)
                {
                    r=0;x=i;y=j;
                    for (i1=0;i1<=k;i1++)
                        r=r+v[x+i1][y]+v[x+i1][y+k];
                    for (i1=1;i1<=k-1;i1++)
                        r=r+v[x][k+y]+v[x+k][k+y];
                    rez=max(rez,r);
                    }
            }
    printf("%d\n",rez);
}