#include <bits/stdc++.h>
#pragma comment(linker, "/stack:225450978")
#pragma GCC optimize("Ofast")
using namespace std;
const long long Mod = 1000000007LL, INF = 1e9, LINF = 1e18;
const long double Pi = 3.141592653589793116, EPS = 1e-9,
                  Gold = ((1 + sqrt(5)) / 2);
long long keymod[] = {1000000007LL, 1000000009LL, 1000000021LL, 1000000033LL};
long long keyCount = sizeof(keymod) / sizeof(long long);
template <class T>
int getbit(T s, int i) {
  return (s >> i) & 1;
}
template <class T>
T onbit(T s, int i) {
  return s | (T(1) << i);
}
template <class T>
T offbit(T s, int i) {
  return s & (~(T(1) << i));
}
template <class T>
int cntbit(T s) {
  return __builtin_popcountll(s);
}
auto TimeStart = chrono::steady_clock::now();
auto TimeEnd = chrono::steady_clock::now();
void ControlIO(int argc, char* argv[]);
void TimerStart();
void TimerStop();
void Exit();
string cppstr_infile = "FILE.IN";
string cppstr_outfile = "FILE.OUT";
long long s, x, ans = 1;
void Input() { cin >> s >> x; }
void Solve() {
  if (s < x) {
    cout << "0";
    return;
  }
  if ((s - x) % 2 != 0) {
    cout << "0";
    return;
  }
  long long a = (s - x) / 2, ans = 1;
  for (long long i = 0; i < 42; i++) {
    if ((x & (1LL << i)) == 0) continue;
    if ((a & (1LL << i)) > 0)
      ans *= 0;
    else
      ans *= 2;
  }
  if (s == x) ans -= 2;
  cout << ans;
}
int main(int argc, char* argv[]) {
  ControlIO(argc, argv);
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  Input();
  TimerStart();
  Solve();
  TimerStop();
  return 0;
}
void ControlIO(int argc, char* argv[]) {
  char* infile = new char[cppstr_infile.size() + 1];
  char* outfile = new char[cppstr_outfile.size() + 1];
  strcpy(infile, cppstr_infile.c_str());
  strcpy(outfile, cppstr_outfile.c_str());
}
void TimerStart() {}
void TimerStop() {}
void Exit() {
  TimerStop();
  exit(0);
}
