#include <cstring>
#include <iostream>
#include <fstream>
#include <vector>
#include <deque>
using namespace std;

int n;
int a[55][55];

ifstream f("collar.in");

int main()
{
    cin >> n;
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= n; j++) {
            cin >> a[i][j];
        }
    }

    int mx = a[1][1];
    for (int i1 = 1; i1 <= n; i1++) {
        for (int j1 = 1; j1 <= n; j1++) {
            for (int i2 = i1 + 1, j2 = j1 + 1; i2 <= n && j2 <= n; i2++, j2++) {
                int sum = 0;
                for (int k = i1; k <= i2; k++) {
                    sum += a[k][j1];
                    sum += a[k][j2];
                }
                for (int k = j1 + 1; k < j2; k++) {
                    sum += a[i1][k];
                    sum += a[i2][k];
                }
                mx = max(mx, sum);
            }
        }
    }

    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= n; j++) {
            mx = max(mx, a[i][j]);
        }
    }
    cout << mx << endl;

    return 0;
}