# define _CRT_SECURE_NO_WARNINGS 1
# include <iostream>
# include <string>
# include <vector>
# include <algorithm>
# include <cstdlib>
# include <cstdio>
# include <cstring>
# include <cstdlib>
# include <iomanip>
# include <queue>
# include <sstream>
# include <climits>
# include <cmath>
# include <list>
# include <functional>
# include <map>
# include <stack>
using namespace std;
# define M_PI 3.141592
# define FOR(i,n) for(int i=0;i<(int)n;i++)
# define FORI(i,k,n) for(int i=k;i<(int)n;i++)
# define toRad 2.0*M_PI/360.0
# define inin(x) int x;cin>>x;
# define all(x) x.begin(),x.end()
# define debug(x) cout<<#x<<" :"<<x<<endl;
# define rep(i,n) for(int i=0;i<(int)n;i++)
# define EPS 1e-12
# define pri_max 60000
typedef pair<int, int> pii;
typedef pair<double, double> pdd;
typedef vector<int> vi;
typedef vector<vi> vvi;

int main()
{
	int n;
	int m[101][101] = {};
	cin >> n;
	for (int i = 1; i <= n; i++)
	{
		for (int j = 1; j <= n; j++)
		{
			cin >> m[i][j];
		}
	}
	for (int i = 0; i <= n; i++)
	{
		for (int j = 1; j <= n; j++)
		{
			m[i][j] += m[i][j - 1];
		}
	}
	for (int j = 0; j <= n; j++)
	{
		for (int i = 1; i <= n; i++)
		{
			m[i][j] += m[i - 1][j];
		}
	}
	int ans = -1000000000;
	for (int i = 1; i <= n; i++)
	{
		for (int j = 1; j <= n; j++)
		{
			for (int x = 1; x + j-1 <= n; x++)
			{
				for (int y = 1; y + i-1 <= n; y++)
				{
					ans = max(ans, m[i - 1][j - 1] + m[i + y - 1][j + x - 1] - m[i - 1][j + x - 1] - m[i + y - 1][j - 1]);
				}
			}
		}
	}
	cout << ans << endl;
}