#include <bits/stdc++.h>
using namespace std;
int n;
int a[125][125];
int sum[125][125]; // sum[i][j] = sum(a[1][1]~a[i][j])
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin >> n;
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= n; j++)
            cin >> a[i][j];
    // 预处理 sum[i][j]
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= n; j++)
            sum[i][j] = sum[i - 1][j] +
                        sum[i][j - 1] +
                        (-sum[i - 1][j - 1]) +
                        a[i][j];
    // 枚举子矩形（左上角 (x,y) 右下角 (xx,yy)）
    int ans = a[1][1];
    for (int x = 1; x <= n; x++)
        for (int y = 1; y <= n; y++)
            for (int xx = x; xx <= n; xx++)
                for (int yy = y; yy <= n; yy++)
                {
                    int now = sum[xx][yy] +
                              (-sum[xx][y - 1]) +
                              (-sum[x - 1][yy]) +
                              sum[x - 1][y - 1];
                    ans = max(ans, now);
                }
    cout << ans << "\n";
    return 0;
}