#include<iostream>

using namespace std;

int n, a[60][60], maxs;
int i1, j, i2, j2;
void citire()
{
	cin>>n;
	for(int i=1; i<=n; i++)
		for(int j=1; j<=n; j++)
			cin>>a[i][j];
}

int suma(int i1, int j, int i2, int j2)
{
	int s=0;
	int i, b;
	for(i=i1; i<=i2; i++)
		s=s+a[i][j];
	for(b=j+1; b<=j2; b++)
		s=s+a[i2][b];
	for(i=i2-1; i>=i1; i--)
		s=s+a[i][j2];
	for(b=j2-1; b>j; b--)
		s=s+a[i1][b];
	return s;
}

int main()
{
	int s;
	int j;
	citire();
	maxs=-32000;
	for(i1=1; i1<=n; i1++)
		for(j=1; j<=n; j++)
			for(i2=i1; i2<=n; i2++)
				{
					s=suma(i1, j, i2, i2+j-i1);
					if(s>maxs)
						maxs=s;
				}
	cout<<maxs;
	return 0;
}