//	Q.A.2
//	John Wang
// 	Goal: Read the radius and out the area of the circle

import java.text.DecimalFormat;
import java.util.Scanner;

class QA916_2
{
	public static void main(String[] args)
	{
		Scanner input = new Scanner(System.in);
		DecimalFormat f2 = new DecimalFormat("0.00");

		System.out.print("Redius: ");
		double r = input.nextDouble();
		double area = Math.PI * r * r;

		System.out.println("Answer = " + f2.format(area) + "\n\n\n");
	}
}