using System;

public class Program
{
    public void Main(string[] args)
    {
        if (int.TryParse(Console.ReadLine(), out number))
        {
            Console.WriteLine(number * 2);
        }
        else
            Console.WriteLine("Invalid input!\nInteger was asked.");

        Console.WriteLine("Press a key to exit the program...");
        Console.ReadKey();
    }
}