# Weekly Challenge: Maximizing XOR

Given two integers, `L`

and `R`

, find the maximal value of `A`

xor `B`

, where `A`

and `B`

satisfy the following condition:

L ≤ A ≤ B ≤ R

**Input Format**

The input contains two lines; `L`

is present in the first line and `R`

in the second line.

**Constrains**

1 ≤ L ≤ R ≤ 10^{3}

**Output Format**

The maximal value as mentioned in the problem statement.

**Sample Input**

10 15

**Sample Output**

7

**Explanation**

The input tells us that `L = 10`

and `R = 15`

. All the pairs which comply to above condition are the following:

10 ⊕ 10 = 0 10 ⊕ 11 = 1 10 ⊕ 12 = 6 10 ⊕ 13 = 7 10 ⊕ 14 = 4 10 ⊕ 15 = 5 11 ⊕ 11 = 0 11 ⊕ 12 = 7 11 ⊕ 13 = 6 11 ⊕ 14 = 5 11 ⊕ 15 = 4 12 ⊕ 12 = 0 12 ⊕ 13 = 1 12 ⊕ 14 = 2 12 ⊕ 15 = 3 13 ⊕ 13 = 0 13 ⊕ 14 = 3 13 ⊕ 15 = 2 14 ⊕ 14 = 0 14 ⊕ 15 = 1 15 ⊕ 15 = 0Here two pairs

`(10, 13)`

and `(11, 12)`

have maximum xor value `7`

, and this is the answer.
This challenge was created by zxqfd555 and posted on hackerrank.com.

Starts on Tue, 1 November 2016 10:00

Ends on Sun, 6 November 2016 10:00

Points you can get: 7