#include <iostream>
#include <algorithm>

using namespace std;

int ans[2001][2001];
int n,m,i,a,b,k,j,x,y;
char s[102];

int slv( int i, int j, int x, int y )
{
    int b = 0;
    for( int k = i ; k <= x ; k++ )
        b += ans[ k ][ j ] + ans[ k ][ y ];
    for( int k = j ; k <= y ; k++ )
        b += ans[ i ][ k ] + ans[ x ][ k ];
    return b-ans[i][j]-ans[i][y]-ans[x][j]-ans[x][y];
}

int main()
{
    cin>>n;
    m = n;
    a = -10000000;
    for( i = 1 ; i <= n ; i++ )
    for( j = 1 ; j <= m ; j++ )
        cin>>ans[ i ][ j ],a=max(a,ans[i][j]),a=max( a , max( ans[i][j]+ans[i][j-1] , ans[i][j]+ans[i-1][j] ) );
    for( i = 1 ; i <= n ; i++ )
    for( j = 1 ; j <= m ; j++ )
    for( x = i + 1 ; x <= n ; x++ )
    for( y = j + 1 ; y <= m ; y++ )
        a = max( a , slv( i , j , x , y ) );
    cout<<a;

return 0;
}