Problem Statement

You are given integers A and B between 0 and 255 (inclusive). Find a non-negative integer C such that $A \text{ xor }C=B$.
It can be proved that there uniquely exists such C, and it will be between 0 and 255 (inclusive).

What is bitwise $\mathrm{XOR}$?

The bitwise $\mathrm{XOR}$ of integers A and B, A\ $\mathrm{XOR}$\ B, is defined as follows:

• When A\ $\mathrm{XOR}$\ B is written in base two, the digit in the 2^k'$s place (k \geq 0)$ is 1 if exactly one of A and B is 1, and 0 otherwise.

  For example, we have 3\ $\mathrm{XOR}$\ 5 = 6 (in base two: 011\ $\mathrm{XOR}$\ 101 = 110).
  

Input

Input is given from Standard Input in the following format:
A B

Output

Print the answer.

Constraints

• $0\leq A,B \leq 255$
• All values in input are integers.

Sample Input 1

3 6

Sample Output 1

5

When written in binary, 3 will be 11, and 5 will be $101. Thus, their \text{xor}$ will be 110 in binary, or 6 in decimal.
In short, $3 \text{ xor } 5 = 6$, so the answer is 5.

Sample Input 2

10 12

Sample Output 2

6

见题面 Input 部分

见题面 Output 部分