#include<fstream>
#define L 101
using namespace std;

int m[L][L],j1,i1,i,j,nr,maxim,suma,n,k,min2;
int main ()
{
	ifstream f("joctv.in");
	ofstream g("joctv.out");

	f>>n;
 for(i=1;i<=n;++i)
	for(j=1;j<=n;++j)
		f>>m[i][j];
 for(i=1;i<=n;++i)
	for(j=1;j<=n;++j)
		m[i][j]=m[i][j]+m[i-1][j]+m[i][j-1]-m[i-1][j-1];
for(i=0;i<n;++i)
	for(j=i+1;j<=n;++j)
	{
		int max=-200,min=0;
		for(k=1;k<=n;++k)
		{
			nr=m[j][k]-m[i][k];
			if(nr<min)
			{
				min2=min;
				min=nr;
				if(nr-min2>max)
					max=nr-min2;
			}
			else
				if(nr-min>max)
					max=nr-min;
		}
		if(max>maxim)
			maxim=max;
	}
g<<maxim;
return 0;
}