#include <stdio.h>

#define NMAX 55

using namespace std;

int A[NMAX][NMAX],N,MAX=0;

void read()
{
    scanf("%d\n",&N);
    for (int i=1;i<=N;i++)
        for (int j=1;j<=N;j++)
            scanf("%d ",&A[i][j]);
}

int calc(int x1,int y1,int x2,int y2)
{
    int sum=0;
    for (int i=x1;i<=x2;i++)
        sum=sum+A[i][y1]+A[i][y2];

    for (int j=y1;j<=y2;j++)
        sum=sum+A[x1][j]+A[x2][j];

    sum=sum-A[x1][y1]-A[x2][y1]-A[x2][y2]-A[x1][y2];

    return sum;
}

void solve()
{
    int i,j,k,l;


    for (int i=1;i<=N;i++)
        for (int j=1;j<=N;j++)
            for (int k=i;k<=N;k++)
                for (int l=j;l<=N;l++)
                    if (calc(i,j,k,l)>MAX && (k-i)==(l-j)) MAX=calc(i,j,k,l);

    printf("%d\n",MAX);
}

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

    read();
    if (N==1) printf("%d\n",A[1][1]);
    else
        solve();

    fclose(stdin);
    fclose(stdout);
    return 0;
}