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Problems

Invert a bit

Invert a bit

Time limit 1 second
Memory limit 128 MiB

Two integers а and k are given. Print number that is obtained from а by inverting the k-th bit.

Input data

One line contains two integers a and k (0a10^9).

Output data

Print the number a with k-th bit inverted.

Examples

Input example #1
5 1
Output example #1
7
Source 2010 LKSH Berendevy Polyany, August, Parallel C, Day 1, Problem C