B. ZYW with his score
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output

As we all know, ZYW is a master of roll. Now, at the end of this term, everyone wants to know how many points ZYW has scored. But ZYW believes that only people who are intelligent enough can know his score. So he told you his encrypted score.

There are only two courses in this semester. Let's assume that ZYW's scores are $$$a$$$ and $$$b$$$, respectively. He will tell you $$$a+b$$$ and $$$a\ \And \ b$$$. Can you tell the value of $$$a\oplus b$$$?

"$$$\And$$$" and "$$$\oplus$$$" represents bitwise AND and XOR operation, respectively.

Input

The input consists of two integers $$$a+b$$$ and $$$a\ \And\ b\ (0\le a,b \le 10^9)$$$.

Output

Output an integer representing $$$a\oplus b$$$.

Example
Input
5 2
Output
1