#include <iostream>
#include <vector>

using namespace std;

vector< vector<int> > d; //массив для динамики

int get_sum(int x1, int x2, int y1, int y2)
{
    if (x1 == 1 && y1 == 1) {
        return d[x2][y2];
    } else if (x1 == 1) {
        return d[x2][y2] - d[x2][y1 - 1];
    } else if (y1 == 1) {
        return d[x2][y2] - d[x1 - 1][y2];
    } else {
        return d[x2][y2] - d[x2][y1 - 1] - d[x1 - 1][y2] + d[x1 - 1][y1 - 1];
    }
}

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

    vector< vector<int> > a(n, vector<int> (n)); //данная матрица
    d.resize(n + 1, vector<int> (n + 1));

    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < n; ++j)
            cin >> a[i][j];
    }

    for (int i = 1; i < n + 1; ++i) {
        d[i][1] = a[i - 1][0] + d[i - 1][1];
        d[1][i] = a[0][i - 1] + d[1][i - 1];
    }

    for (int i = 2; i < n + 1; ++i) {
        for (int j = 2; j < n + 1; ++j) {
            d[i][j] = d[i - 1][j] + d[i][j - 1] + a[i - 1][j - 1] - d[i - 1][j - 1];
        }
    }

    int max_sum = -1e9;

    for (int x1 = 1; x1 < n + 1; ++x1) {
        for (int x2 = x1; x2 < n + 1; ++x2) {
            for (int y1 = 1; y1 < n + 1; ++y1) {
                for (int y2 = y1; y2 < n + 1; ++y2) {
                    max_sum = max(max_sum, get_sum(x1, x2, y1, y2));
                }
            }
        }
    }

    cout << max_sum << endl;

    return 0;
}