POJ 2405

 #include <iostream>
 #include <cmath>
 #include <iomanip>
 #define pi 3.1415926536

 using namespace std;

 int main()
 {
     //freopen("acm.acm","r",stdin);
     double D;
     double V;
     double ans;
     while(cin>>D>>V,D)
     {
     //    ans = pow(D*D*D-6*V/PI,1.0/3.0);
         ans = pow((D*D*D-6.0*V/pi),1.0/);
         cout<<setiosflags(ios::fixed)<<setprecision()<<ans<<endl;
     }
 }