using System;

public class Hello
{
    public static int now, x, ans;
    static void Main()
    {
         x = int.Parse(Console.ReadLine().Trim());
        getAns();
    }
    static bool aa ()
    {
        ans += 2;
        now += 2;
        return now == x;
    }
    static bool bb()
    {
        ans++;
        now--;
        return now == x;
    }
    static void getAns()
    {
        now = 0;
        while (true)
        {
            if (aa()) { Console.WriteLine(ans);return; }
            if (aa()) { Console.WriteLine(ans); return; }
            if (bb()) { Console.WriteLine(ans); return; }
            if (bb()) { Console.WriteLine(ans); return; }
            if (aa()) { Console.WriteLine(ans); return; }
            if (bb()) { Console.WriteLine(ans); return; }
            if (bb()) { Console.WriteLine(ans); return; }
        }
    }
}