#include<stdio.h>
#include<algorithm>
#include<vector>

#define maxdim 53
#define inf (1<<30)

using namespace std;

int n;
int a[maxdim][maxdim],Sup[maxdim][maxdim],Sleft[maxdim][maxdim];

int main () {
	
	#ifndef ONLINE_JUDGE
	freopen("a.in","r",stdin);
	freopen("a.out","w",stdout);
	#endif
	
	scanf("%d",&n);
	for ( int i = 1 ; i <= n ; ++i ){
		for ( int j = 1 ; j <= n ; ++j ){
			scanf("%d",&a[i][j]);
			Sup[i][j] = Sup[i-1][j]+a[i][j];
			Sleft[i][j] = Sleft[i][j-1]+a[i][j];
		}
	}
	
	int sol = -inf;
	for ( int x = 1 ; x <= n ; ++x ){
		for ( int y = 1 ; y <= n ; ++y ){
			
			sol = max(sol,a[x][y]);
			for ( int l = 1 ; x+l <= n && y+l <= n ; ++l ){
				int x2 = x+l,y2 = y+l;
				
				int now = Sleft[x][y2]-Sleft[x][y-1];
				now += Sleft[x2][y2]-Sleft[x2][y-1];
				now += Sup[x2-1][y]-Sup[x][y];
				now += Sup[x2-1][y2]-Sup[x][y2];
				
				sol = max(sol,now);
			}
		}
	}
	
	printf("%d\n",sol);
	
	return 0;
}