package tasks;

import java.util.Scanner;

/**
 * Created by Admin on 23.04.2017.
 */
public class lengthCircle {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.print("Please, input radius: ");
        double r = sc.nextDouble();
        double l = Math.PI * Math.pow(r, 2);
        System.out.println(l);
    }
}