I think that all correct or mistake on variable???
//#1084
#include<iostream>
#include<math.h>

int main()
{
 using namespace std;

 long j=1,k,R,L;
 double s,pi=3.1415926535;
  cin>>L>>R;

   if(L>=2*R)
    s=pi*R*R;
 else
     if (R>(L*sqrt(2.0))/2) s=L*L;
else
 s=2*R*R*atan((L*L-2*R*R)/(L*sqrt((double) 4*R*R-L*L)))+L*sqrt((double) 4*R*R-L*L);

k=s;

while(k>10)
   {
   k=k/10;
   j++;
   }
   cout.precision( 3+j );
   cout << noshowpoint << s << endl;

 return 0;
}