Дистанционный практикум по программированию

One can determine the Gray code by its number using a very simple function: G(x) = x xor (x div 2), where xor stands for bitwise exclusive OR (bitwise modulo 2 addition), and div means integer division. It is interesting to note that function G(x) is invertible, which means it is always possible to uniquely restore x given the value of G(x).

Write a program to restore number x from the given value of G(x).

 

Limitations

0 <= x, y <= 10⁹.

 

Input

The input file contains an integer number y, the value of G(x).

 

Output

The output file should contain a single integer x such that G(x) = y.

 

Example

Input	Output
15	10

 

Input	Output
1723	1234

 

All Rybinsk-2012 problems (in PDF)