#include	<vector>
#include	<iostream>
#include	<fstream>
#include	<algorithm>

using namespace std;

int n ;
int A[52][52] ;
int ss = -(0x3fefefef) ;

int calcSum (int i1, int j1 , int lat)
{
    int k ;
    int S = 0 ;
    for(k = 0 ; k < lat ; ++k)
        S += ( A[i1+k][j1]+A[i1+k][j1+lat-1] ) ;

    for(k = 1 ; k < lat-1 ; ++k)
        S += ( A[i1][j1+k]+A[i1+lat-1][j1+k] ) ;

        return (S) ;
}

int main(){
//    freopen("a.in","r",stdin) ;

    cin >> n ;

    for(int i = 1 ; i <= n ; ++i)
        for(int j = 1 ; j <= n ; ++j)
            cin >> A[i][j];

    if ( n == 1){
        cout << A[1][1] << '\n' ;
        return 0 ;
    }


    for(int i = 1 ; i <= n ; ++i)
        for(int j = 1 ; j <= n ; ++j)
        {
            for(int x = n - max(i,j) + 1 ; x >= 1 ; --x)
               ss = max ( ss , calcSum(i,j,x)) ;


        }

    cout << ss << '\n' ;




return (0);
}