using System;

public class Program

{

    public static void Main()

    {

        float pi = 3.14159f;

        float radio = 0.0f;

        float area = 0f;

        radio = float.Parse(Console.ReadLine());

​

        area = pi * radio * radio;

​

        Console.WriteLine("A={0:00}\r\n",area);

    }

}