#include <stdio.h>
#include <limits.h>
#define nmax 51

using namespace std;

int A[nmax][nmax], N, i, j, x, y, k, L[nmax][nmax], C[nmax][nmax], maxim;

int main() {
    maxim = INT_MIN;
    int nr;
    scanf ("%d", &N);
    for (i = 1; i <= N; ++i)
        for (j = 1; j <= N; ++j) {
            scanf ("%d", &A[i][j]);
            if (A[i][j] > maxim) maxim = A[i][j];
            L[i][j] = A[i][j] + L[i][j-1];
            C[i][j] = A[i][j] + C[i-1][j];
        }
    int xa, xb, ya, yb;
    for (xb = 1; xb <= N; ++xb)
        for (yb = 1; yb <= N; ++yb)
            for (xa = 1; xa <= xb; ++xa)
                for (ya = 1; ya <= yb; ++ya) {
                    nr = L[xa][yb] - L[xa][ya-1];
                    nr += L[xb][yb] - L[x][ya-1];
                    nr += C[xb][ya] - C[xa-1][ya];
                    nr += C[xb][yb] - C[xa-1][yb];
                    nr -= (A[xa][ya] + A[xa][yb] + A[xb][ya] + A[xb][yb]);
                    if (xa == xb && ya == yb) nr += A[xa][ya];
                    if (nr > maxim) maxim = nr;
                }
    printf ("%d\n", maxim);

    return 0;
}