import java.util.Scanner;  // Demo in BlueJ

public class ComputeArea
{
   public static void main(String[] args)
   {
      Scanner input = new Scanner(System.in); 
      double radius;
      double area;
 
      System.out.print("Enter a radius: ");
      radius = input.nextDouble();    

      if ( radius < 0 )
      {
         System.out.println("Illegal radius");
      }
      else
      {   // Print area of circle
          area = 3.14159 * radius * radius; 
          System.out.println(area);
      }
   }                       
}