#include <cstdio>

using namespace std;

long a [55][55], sp1 [55][55], sp [55][55];

int main () {
    long i, j, n, x, y, s, smax = - 2000000000;

 //   freopen ("m.in", "r", stdin);
    //freopen ("m.out", "w", stdout);

    scanf ("%ld", &n);
    for (i = 1; i <= n; i ++)
        for (j = 1; j <= n; j ++) {
            scanf ("%ld", &a [i][j]);
            sp [i][j] = sp [i][j - 1] + a [i][j];
            sp1 [i][j] = sp1 [i - 1][j] + a [i][j];
        }
    for (i = 1; i <= n; i ++)
        for (j = 1; j <= n; j ++)
            for (x = 1; x <= n; x ++)
                for (y = 1; y <= n; y ++) {
                    s = sp [i][y] - sp [i][j - 1];
                    s = s + sp1 [x][y] - sp1 [i][y];
                    s = s + sp [x][y - 1] - sp [x][j - 1];
                    s = s + sp1 [x - 1][j] - sp1 [i][j];
                    if (s > smax)
                        smax = s;
                }
    printf ("%ld\n", smax);
    return 0;
}