#include<stdio.h>



int main()
{
	int n;
	int sum=0;
	int s=0;
	int a[100][100];
	

	scanf("%d",&n);

	for(int i=0;i<n;i++)
	{
		for( int j=0;j<n;j++)
		{
			scanf("%d",&a[i][j]);   // getting the input into a n*n arrar
			sum+=a[i][j];   // i am making the sum(final sum variable) initialised to the sum of all the input
		}
	}


//--------------------------------------------------------
   
 



  for(int  p=0;p<n;p++)            //  for each element in the 2d arrar  making that element as
  {                                 // left top corner of the rect
	  for( int q=0;q<n;q++)
	  {
		 
		  
		   int r=n;
           int c=n;
		  
		  
		  
		  while(r!=0)           
		  {
			  for(int i=p;i<r;i++)
			  {
				  for(int j=q;j<c;j++)
				  {
					  s+=a[i][j];
				  }
			  }
			  r--;
			  if(s>sum)
				  sum=s;  //if the sum of the now calculated.. rect is greater than sum assin sum=s
			  s=0;
		  }


		 r=n;
		 c=n;



		  while(c!=0)
		  {
			  for(int i=p;i<r;i++)
			  {
				  for(int j=q;j<c;j++)
				  {
					  s+=a[i][j];
				  }
			  }
			  c--;
			  if(s>sum)
				  sum=s;
			  s=0;
		  }

                


  
	  }
  }
//----------------------------

  printf("%d",sum);






	

	return 0;
}