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Little Girl and Maximum XOR

Time Limit
1s
Memory Limit
32768KB
Judge Program
Standard
Ratio(Solve/Submit)
100.00%(1/1)
Description:

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 (labr). Your task is to find the maximum value among all considered ones.

Expression means applying bitwise excluding or operation to integers x and y. The given operation exists in all modern programming languages, for example, in languages C++ and Java it is represented as "^", in Pascal — as «xor».

Input:

The input consists of multiple test cases.

Each test case contains space-separated integers l and r (1 ≤ lr ≤ 1018).

Output:

In a single line print a single integer — the maximum value of for all pairs of integers a, b (labr).

Sample Input:
8 16
Sample Output:
31

Submit