## 0705. Inverse problem to Gray code

###### Time limit : 1000 ms Memory limit : 64 mb

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).

Input

The input file contains an integer number y, the value of G(x) (0≤y≤109).

Output

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

Samples

 № Input Output 1 15 10 2 1723 1234 3 0 0