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?≤?a?≤?b?≤?r). Your task is to find the maximum value among all considered ones.

Expression means applying bitwise excluding or operation to integers x

Input

The single line contains space-separated integers l and r (1?≤?l?≤?r?≤?10¹⁸).

Please, do not use the %lld specifier to read or write 64-bit integers in С++. It is preferred to use the cin, cout streams or the %I64d specifier.

Output

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

Example

1 2

3

8 16

31

1 1

0

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 typedef long long ll;
 4 
 5 ll L,R;
 
 6 
 7 int main()
 8 {   cin>>L>>R;
 9     int i;
10     for(i=63;i>=0;i--) if((L&(1ll<<i))^(R&(1ll<<i))) break;
11     ll ans=pow(2,i+1)-1;
12     cout<<ans<<endl;
13 } 

Little Girl and Maximum XOR CodeForces - 276D