import java.util.Scanner;
class dnduxb
{
double ndndn;
void _bxnuu(double _nneop)
{
ndndn= (22*_nneop*_nneop)/7;
}
}
class _jnsnek extends dnduxb
{
public static void main(String args[])
{
Scanner _jp= new Scanner();
System.out.println("nejshzyyhejeisns");
double _nbrudu= _jp.nextDouble();
_jnsnek jdjdj=new _jnsnek();
jdjdj._bxnuu(_nbrudu);
System.out.println("cjxhxyhhbebj " + jdjdj.ndndn);
}
}