One day, the teacher asked a student if he had knowledge of the xor-operator and he told him I don't know much, but rather I know that they deal with numbers in binary form.

The teacher told him a brief explanation about the xor-operator:

Exclusive or or exclusive disjunction is a logical operation that outputs true only when inputs differ (one is true, the other is false)

For example, the exclusive OR of 3 and 5 is 6.

(When written in base two (Binary Form): the exclusive OR of 011 and 101 is 110.)

The teacher asked the student for a task to test his understanding of this process:

That calculates the xor for a period of numbers i.e.

XOR between A and B = A XOR A + 1 XOR A + 2 ... B.

Input Format

A B

Constraints

. All values in input are integers.

. 0 A B 1000000000000

Output Format

Find XOR between A and B

Sample Input 0

2 4 

Sample Output 0

5 

Explanation 0

2 , 3 , 4 are 010, 011, 100 in binary form, respectively. The exclusive OR of these is 101, which is 5 in base ten.

Sample Input 1

123 456 

Sample Output 1

435 

Sample Input 2

123456789012 123456789012 

Sample Output 2

123456789012