using System;

                    ;

public class groupf 

{

    public static void Main()

    {

    double PI=3.14;

    int perimetr, n ;  

    Console.Write (" ENTER THE N:" );

    N= int.Parse(Console.Readline());

    perimeter = 2 * N * PI

    Console.WriteLine("Perimetr={0}",permeter);

}