#include "bits/stdc++.h"
#define REP(i, n) for(int i = 0; i < int(n); i++)
#define FOR(i,n,m) for(int i = int(n); i < int(m); i++)
using namespace std;
typedef long long ll;
const int MOD = 1e9 + 7;
const int INF = 1e9 + 6;
const ll LLINF = 1e18 + 1;

int bitpopcount(ll n) {
    int res = 0;
    while (n) {
        if (n & 1) res++;
        n >>= 1;
    }
    return res;
}

int main() {
    ll a, b; cin >> a >> b;
    if ((a | b) != b) {
        cout << 0 << endl;
        return 0;
    }
    if (a == b) {
        cout << 1 << endl;
        return 0;
    }
    cout << ll(pow(2LL, bitpopcount(a^b) - 1)) << endl;
    return 0;
}