#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main() {
    int n;
    cin >> n;
    vector <vector <int>> a(n, vector <int> (n));
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            cin >> a[i][j];
        }
    }
    int ans = a[0][0];
    for (int leng = 1; leng <= n; leng++){
        for (int up = 0; up <= n-leng; up++){
            vector <long long> sumv(n);
            for (int j = 0; j < n; j++) {
                for (int i = up; i < up + leng; i++) {
                    sumv[j] += a[i][j];
                }
            }
            int sum = 0;
            for (int r = 0; r < n; ++r) {
                sum += sumv[r];
                ans = max(ans, sum);
                sum = max(sum, 0);
            }
        }
    }
    cout << ans;
}