Toggle the bit

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.

Examples

Input
Output
9 2
13
9 3
1

Explanation

  • 9 β†’ 1001 β‡’ toggle bit at index 2 β‡’ 1101 β‡’ 13
  • 9 β†’ 1001 β‡’ toggle bit at index 3 β‡’ 0001 β‡’ 1
Β 

Constraints

Time limit: 2 seconds

Memory limit: 512 MB

Output limit: 1 MB

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