#include <iostream>
#include <vector>
#include <algorithm>
#include <iomanip>
#include <string>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <tuple>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <climits>
#include <cassert>
#include <cstdint>
#include <numeric>
#include <bitset>
#include <functional>

using namespace std;

using ll =  long long;
using Pll = pair<ll, ll>;
using Pii = pair<int, int>;

constexpr ll MOD = 1000000007;
constexpr long double EPS = 1e-10;
constexpr int dyx[4][2] = {
    { 0, 1}, {-1, 0}, {0,-1}, {1, 0}
};

int main() {
    ios::sync_with_stdio(false); cin.tie(nullptr);
    ll a, b;
    cin >> a >> b;

    ll ans = 1LL;
    for(int i=0;i<31;++i) {
        if((a >> i) & 1) {
            if((b >> i) & 1) {
                continue;
            } else {
                ans = 0LL;
                break;
            }
        } else {
            if((b >> i) & 1) {
                ans *= 2LL;
            } else {
                continue;
            }
        }
    }

    if(ans != 1LL) ans /= 2LL;
    cout << ans << endl;

}