#include <iostream>
#include <math.h>


using namespace std;

int h1,b1;



int main()
{
  double  pi= 2*acos(0);//3.14161f;

  freopen("cylinder.in","r",stdin);
 
  
  	while(1)
	{
	
	
	 
	
	  scanf("%d",&h1);
	  scanf("%d",&b1);
	  
	  if(h1==0||b1==0)break;
	  
	  double h=h1;
	  double b=b1;
	  
	  if(b>h)
	  {
	    double temp;
	    temp=b;
	    b=h;
	    h=temp;
	    	  
	  }
	  
	  double leng;
	  double res,res2,res3;
	  
	  
	  res= b/2.f;
	  leng= b;
	  
	  
	  
	  
	  
	  if(h<2.f*(pi+1.f)*res)
	  {
		res= (h/2.f/(pi+1.f));
			
	  
	  }
	
	  res2 = pi*res*res* leng ;
	  
	  res= b/2.f/pi;
	 
	    leng= h-(2.f*res);
	
	
	  
	  res3 = pi*res*res* leng ;
	  
	  if(res3>res2)  printf("%.3f",res3);
	  else   printf("%.3f",res2);
	  cout << endl;
	
	  //cout << endl;*/
	  
	
	
	
	}
	
	
	
	
	
	
	
  
  
  

  return 0;


}