import java.util.*;
import java.lang.*;
import java.io.*;
 
class Main
{
	static BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
	public static void main (String[] args) throws java.lang.Exception
	{
		String s;
		while ((s = in.readLine())!=null) {
			long k = Long.parseLong(s);
			System.out.println(k^(k>>1));
		}
	}
}