#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;

int n, a[55][55], sol, sol1;

int main() {
//freopen("input.txt", "r", stdin);
//__TEST_MODE__ freopen("output.txt", "w", stdout);

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

    for (int i = 1; i <= n; i++)
    for (int j = 1; j <= n; j++)
    for (int k = 1; (i + k - 1) <= n && (j + k - 1) <= n; k++) {
        sol1 = 0;
        if (k == 1) {
            sol1 = a[i][j];
        } else {
            for (int l = 0; l < k; l++) sol1 += a[i][j+l] + a[i+k-1][j+l] + a[i+l][j] + a[i+l][j+k-1];
            sol1 += - a[i][j] - a[i+k-1][j] - a[i][j+k-1] - a[i+k-1][j+k-1];
        }
        sol = max(sol, sol1);
    }
    cout << sol;

    return 0;
}