Problem:
Score : 900 points

Problem Statement

Nukes has an integer that can be represented as the bitwise OR of one or more integers between A and B (inclusive).
How many possible candidates of the value of Nukes's integer there are?

Constraints

1 ≤ A ≤ B < 2^{60}

A and B are integers.

Input

The input is given from Standard Input in the following format:

A
B

Output

Print the number of possible candidates of the value of Nukes's integer.

Sample Input 1

7
9

Sample Output 1

4

In this case, A=7 and B=9. There are four integers that can be represented as the bitwise OR of a non-empty subset of {7, 8, 9}: 7, 8, 9 and 15.

Sample Input 2

65
98

Sample Output 2

63

Sample Input 3

271828182845904523
314159265358979323

Sample Output 3

68833183630578410

Solution in C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <cstdio>
#include <algorithm>
using namespace std;
typedef long long ll;
ll A, B, r, k, ans;
int main() {
    scanf("%lld %lld", &A, &B);
    for(r = 60; (A >> r) == (B >> r); --r);
    A &= (1LL << (r + 1)) - 1;
    B &= (1LL << (r + 1)) - 1;
    for(k = r - 1; ~B >> k & 1; --k);
    ll ans = ((1LL << r) - A) + min(1LL << r, (1LL << (k + 1)) + ((1LL << r) - A));
    printf("%lld\n", ans);
    return 0;
}