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

const int MAXN = 52;
const int INF = 0x3f3f3f3f;

int n, a[MAXN][MAXN], partSum[MAXN][MAXN];

int getSum(int x, int y, int k) {
    int sum = 0;
    if (k == 1) return a[x][y];

    for (int i = 1; i < k - 1; ++i)
        sum += a[x + i][y] + a[x][y + i] + a[x + i][y + k - 1] + a[x + k - 1][y + i];
    sum += a[x][y] + a[x + k - 1][y + k - 1];
    sum += a[x][y + k - 1] + a[x + k - 1][y];

    return sum;

}

int main() {
    //#ifndef ONLINE_JUDGE
    //freopen("a.in", "r", stdin);
    //#endif // ONLINE_JUDGE

    cin >> n;

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

    int rez = -INF;
    for (int i = 1; i <= n; ++i)
        for (int j = 1; j <= n; ++j) {
            for (int k = 1; k + i - 1 <= n && k + j - 1 <= n; ++k) {
                rez = max(rez, getSum(i, j, k));
            }
        }
    cout << rez;
    return 0;
}