Given an integer n, you are asked to toggle its i-th bit (turn 0 into 1 and 1 into 0).

Input

The input contains two integers n (1 ≤ n ≤ ) and i separated by a space. It’s guaranteed that i is smaller than the length of the binary representation of n.

Output

The program should print the resulting number after toggling the i-th bit of n.