#include <cstdio>
#include <algorithm>
using namespace std;

#define Nmax 64
int A[Nmax][Nmax];
int L[Nmax][Nmax];
int C[Nmax][Nmax];

int N;

int main() {
//    freopen("test.in", "r", stdin);
    
    scanf("%d", &N);
    int best = -1000000000;

    for (int i=1; i<=N; ++i)
        for (int j=1; j<=N; ++j) {
            scanf("%d", &A[i][j]);
            L[i][j] = L[i][j-1] + A[i][j];
            C[i][j] = C[i-1][j] + A[i][j];
            best = max(best, A[i][j]);
        }
    
    for (int i=1; i<=N; ++i)
        for (int j=1; j<=N; ++j)
            for (int k=j; k<=N; ++k){
                best = max(best, C[k][i] - C[j-1][i]);
                best = max(best, L[i][k] - L[i][j-1]);
        }
    
    for (int i=1; i<=N; ++i)
        for (int j=1; j<=N; ++j)
            for (int x=i+1; x<=N; ++x)
                for (int y=j+1; y<=N; ++y) {
                    int v1 = L[i][y] - L[i][j-1] + L[x][y] - L[x][j-1];
                    int v2 = C[x][j] - C[i-1][j] + C[x][y] - C[i-1][y];
                    best = max(best, v1+v2-A[i][j]-A[x][j]-A[i][y]-A[x][y]);
                }
    printf("%d\n", best);
    
    return 0;
}