Create Maximizing XOR.py

Given two integers: L and R,

find the maximal values of A xor B ∀ L ≤ A ≤ B ≤ R

Input Format
The input contains two lines, L is present in the first line. 
R in the second line.

Constraints
1 ≤ L ≤ R ≤ 103

Output Format
The maximal value as mentioned in the problem statement.

Sample Input

1
10
Sample Output

15
Explanation

The maximum value can be obtained for A = 5 and B = 10,

1010 xor 0101 = 1111 hence 15.