CF276D Little Girl and Maximum XOR

A little girl loves problems on bitwise operations very much. Here's one of them. You are given two integers $ l $ and $ r $ . Let's consider the values of  for all pairs of integers $ a $ and $ b $ $ (l

The single line contains space-separated integers $ l $ and $ r $ ( $ 1

In a single line print a single integer — the maximum value of  for all pairs of integers $ a $ , $ b $ $ (l