//My name is "I suck dick for metsuro's help"

import java.util.Scanner;
public class homework5 {
  public static void main (String[] args)
  {
    Scanner input = new Scanner(System.in);

    switch( input.nextInt()) {
      case 1: {
               double r= input.nextDouble();
               double a=  Math.PI*r*r;
               System.out.format("%,.2f.%n", a);

               };
       case 2: {
               double l= input.nextDouble();
               double w= input.nextDouble();
               double a=l*w;
               System.out.format("%,.2f.%n", a);

               };

      default: break;
                            }
  }
}