#include<iostream>
using namespace std;
int a[51][51];
int suml[51][51];
int sumc[51][51];
int main()
{
	int n;
	int mx=-2000000000,val;
	int i,j,i1,j1;
	cin>>n;
	for(i=1;i<=n;i++)
		for(j=1;j<=n;j++)
		{
			cin>>a[i][j];
			suml[i][j]=a[i][j]+suml[i][j-1];
			sumc[i][j]=a[i][j]+sumc[i-1][j];
		}
	for(i=1;i<=n;i++)
		for(j=1;j<=n;j++)
			for(i1=i;i1<=n;i1++)
				for(j1=j;j1<=n;j1++)
				{
					if(i==i1)
						val=sumc[i][j1]-sumc[i][j-1];
					else
					{
						if(i1-i==1)
							val=sumc[i][j1]-sumc[i][j-1]+sumc[i1][j1]-sumc[i1][j-1];
						else
						{
							if(j==j1)
								val=suml[i1][j]-suml[i-1][j];
							else
							{
								if((j1-j)==1)
									val=suml[i1][j]-suml[i-1][j]+suml[i1][j1]-suml[i-1][j1];
								else
									val=suml[i1][j1]-suml[i1][j-1]+suml[i1][j]-suml[i-1][j]+sumc[i1-1][j]-sumc[i][j]+sumc[i1-1][j1]-sumc[i][j1];
									
							}
						}
					}
					
					//val=suml[i1][j1]-suml[i1][j-1]+suml[i1][j]-suml[i-1][j]+sumc[i1][j]-sumc[i-1][j]+sumc[i1][j1]-sumc[i-1][j1]-a[i][j]-a[i][j1]-a[i1][j]-a[i1][j1];
					if(val>mx)
						mx=val;
				}
	cout<<mx<<'\n';
	return 0;
}