#include<iostream>
#include<vector>
using namespace std;

vector<vector<int> > build_sum_table(vector<vector<int> > table) {
    vector<vector<int> > sum_table = {};
    for (int i = 0; i < table.size(); i++) {
        vector<int> sum_line = {0};
        for (int j = 0; j < table[0].size(); j++) {
            sum_line.push_back(sum_line[j] + table[i][j]);
        }
        sum_table.push_back(sum_line);
    }
    return sum_table;
}

int find_sum(vector<vector<int> > sum_table, int x1, int x2, int y) {
    return sum_table[y][x2 + 1] - sum_table[y][x1];
}

int find_gsum(vector<vector<int> > table) {
    vector<vector<int> > sum_table = build_sum_table(table);
    int gsum = table[0][0];
    for (int x2 = 0; x2 < table[0].size(); x2++) {
        for (int x1 = 0; x1 <= x2; x1++) {
            int imax = find_sum(sum_table, x1, x2, 0);
            for (int y = 1; y < table.size(); y++) {
                imax += find_sum(sum_table, x1, x2, y);
                if (find_sum(sum_table, x1, x2, y) > imax) {
                    imax = find_sum(sum_table, x1, x2, y);
                }
                if (imax > gsum) {
                    gsum = imax;
                }
            }
        }
    }
    return gsum;
}

int main() {

    int n;
    cin >> n;
    vector<vector<int> > table = {};
    for (int i = 0; i < n; i++) {
        vector<int> line = {};
        for (int j = 0; j < n; j++) {
            int e;
            cin >> e;
            line.push_back(e);
        }
        table.push_back(line);
    }
    cout << find_gsum(table);
}