#include <bits/stdc++.h>

using namespace std;

const int NMax = 1e5 + 5;

int v[55][55];
int A[55][55];
int B[55][55];

int main() {
    int n;
    cin >> n;

    int best = -105;
    for(int i = 1; i <= n; i++) {
        for(int j = 1; j <= n; j++) {
            cin >> v[i][j];
            best = max(best, v[i][j]);
        }
    }

    for(int i = 1; i <= n; i++) {
        for(int j = 1; j <= n; j++) {
            A[i][j] = A[i][j - 1] + v[i][j];
            B[i][j] = B[i - 1][j] + v[i][j];
        }
    }

    for(int i = 1; i <= n; i++) {
        for(int j = 1; j <= n; j++) {
            for(int d = 1; d <= n - max(i, j); d++) {
                int area = 0;
                area += B[i + d][j + d] - B[i - 1][j + d];
                area += B[i + d][j] - B[i - 1][j];
                area += A[i][j + d] - A[i][j - 1];
                area += A[i + d][j + d] - A[i + d][j - 1];
                area = area - v[i][j] - v[i][j + d] - v[i + d][j] - v[i + d][j + d];

                best = max(area, best);
            }
        }
    }

    cout << best;
    return 0;
}