#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>
#include <cmath>
#include <iomanip>
#include <stack>
#include <queue>
#include <numeric>
#include <map>
#include <unordered_map>
#include <set>
#include <fstream>
#include <chrono>
#include <random>
#include <bitset>
#define rep(i,n) for(int i=0;i<(n);i++)
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define sz(x) ((int)(x).size())
#define pb push_back
#define mod 1000000007
using ll = long long;
using namespace std;
ll gcd(ll a, ll b) {return b?gcd(b,a%b):a;}
ll lcm(ll a, ll b) {return a/gcd(a,b)*b;}

/*
   100  100
  |111 &111
   111  100

   101  101
  |110 &110
   111  100
*/

int main(){
  ll A, B; cin >> A >> B;
  int cnt = 0;
  ll ans = 1;
  rep(i,32){
    if(A%2 == 0 && B%2 == 1){
      ans *= 2;
    }
    if(A%2 == 1 && B%2 == 0){
      cout << 0 << endl;
      return 0;
    }
    A /= 2;
    B /= 2;
  }
  cout << max((ll)1,ans/2) << endl;
  return 0;
}