using System;

public class Program

{

    public static void Main()

    {

        double R1 = double.Parse(Console.ReadLine());

        double R2 = double.Parse(Console.ReadLine());

        double S1, S2, S, p= 3.14;

        S1 = p * (R1 * R1);

        S2 = p * (R2 * R2);

        S = S1 - S2;

        Console.WriteLine(S);       

    }

}