#include <cstdio>
#include <cstring>

int a[53][53];
int lin[53][53], col[53][53];

int n;

int main() {
    //freopen ("a.in", "r", stdin);
    scanf ("%d", &n);
    int i, j;
    for (i = 1; i <= n; ++i)
        for (j = 1; j <= n; ++j)
            scanf ("%d ", &a[i][j]);

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

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


    int x1, y1, x2, y2, best = -0x3f3f3f3f;
    int s = 0;
    for (x1 = 1; x1 <= n; ++x1)
        for (y1 = 1; y1 <= n; ++y1)
            for (x2 = x1; x2 <= n; ++x2)
                for (y2 = y1; y2 <= n; ++y2) {
                    s = col[y1][x2] - col[y1][x1 - 1];
                    s += col[y2][x2] - col[y2][x1 - 1];
                    s += lin[x1][y2] - lin[x1][y1 - 1];
                    s += lin[x2][y2] - lin[x2][y1 - 1];
                    s -= a[x1][y1];
                    s -= a[x1][y2];
                    s -= a[x2][y1];
                    s -= a[x2][y2];
                    //printf ("%d %d %d %d: %d\n", x1, y1 ,x2, y2, s);
                    if (x1 == x2 && y1 == y2)
                        s = a[x1][y1];
                    if (x1 == x2 && y1 != y2) {
                        s = lin[x1][y2] - lin[x1][y1 - 1];
                    }
                    if (y1 == y2 && x1 != x2) {
                        s = col[y1][x2] - col[y1][x1 - 1];
                    }
                    if (s > best)
                        best = s;
                }
    printf ("%d\n", best);
}