#include <fstream>

using namespace std;
int n, v[101][101], s[101][101], rezultat, best = -101, rez = 0;
int main()
{
    ifstream f("joctv.in");
    ofstream g("joctv.out");
    f >> n;
    for (int i = 1; i <= n; i++)
    for (int j = 1; j <= n; j++)
    {
        f >> v[i][j];
        s[i][j] += s[i-1][j] + s[i][j-1] - s[i-1][j-1] + v[i][j];
    }
    for (int a = 1; a <= n; a++)
    for (int b = 1; b <= n; b++)
    {
        int mn = 0;
        int kMin = 0;
        for (int i = 1; i <= n; i++)
        {

            rez = s[b][i] - s[a-1][i] - mn;
            if (rez > best) best = rez;
            if (rez < mn )
            {
                mn = rez;
                kMin = i;
            }
        }

    }
    g << best;
    return 0;
}