#include <iostream>
#include <algorithm>

using namespace std ;

const int NMAX = 55 ; 


int N, A[NMAX][NMAX] ; 
int sol, sol1 ; 


int main()
{
	cin >> N ;
	
	for(int i = 1 ; i <= N ; ++ i)
		for(int j = 1 ; j <= N ; ++ j)
			cin >> A[i][j] ; 
			
			
sol = A[1][1] ;


for(int i = 1 ; i <= N ; ++ i)
	for(int j = 1 ; j <= N ; ++ j)
		for(int k = 1 ;  (i + k - 1)  <= N && (j + k - 1) <= N ; ++ k )
		{
			sol1 = 0 ;
			
			if(k == 1)
				sol1 = A[i][j] ;
				
				else {
					for(int l = 0 ; l < k ; ++ l)
						sol1 = sol1 + A[i][j+l] + A[i + k - 1][j + l] + A[i + l][j] + A[i + l][j + k - 1];
						
						sol1 = sol1  - A[i][j] - A[i + k - 1][j] - A[i][j + k - 1] - A[i + k - 1][j + k - 1];
				}
				
				sol = max(sol1, sol) ; 
		}


			cout << sol ;
			
			return  0 ; 
	
}