#include <bits/stdc++.h>
using namespace std;
long long dp[50][2];
long long second, X;
void give(int n, long long c, long long x, long long s) {
  if (x > 1) x = 1;
  if (s > 1) s = 1;
  for (int i = 0; i < 2; i++) {
    for (int j = 0; j < 2; j++) {
      if ((i ^ j) == x and (c + i + j) % 2 == s) {
        dp[n + 1][(c + i + j) / 2] += dp[n][c];
      }
    }
  }
}
inline void ReadInput(void) {
  scanf("%lld", &second);
  scanf("%lld", &X);
}
inline void solve(void) {
  dp[0][0] = 1;
  for (int i = 0; i < 50; i++) {
    give(i, 0, X & (1LL << i), second & (1LL << i));
    give(i, 1, X & (1LL << i), second & (1LL << i));
  }
  if (second == X) dp[49][0] -= 2;
  cout << dp[49][0] << endl;
}
inline void Refresh(void) {}
int main() {
  ReadInput();
  solve();
  return 0;
}
