#include <bits/stdc++.h>
using namespace std;
unsigned long long int dp[2][60];
int main() {
  unsigned long long int s, x;
  cin >> s >> x;
  dp[0][0] = 1;
  unsigned long long int ONE = 1;
  for (int i = 1; i < 50; i++) {
    if ((x & (ONE << (i - 1))) == 0) {
      if ((s & (ONE << (i - 1))) == 0) {
        dp[0][i] += dp[0][i - 1];
        dp[1][i] += dp[0][i - 1];
      } else {
        dp[0][i] += dp[1][i - 1];
        dp[1][i] += dp[1][i - 1];
      }
    } else {
      if ((s & (ONE << (i - 1))) == 0) {
        dp[0][i] = 0;
        dp[1][i] += 2 * dp[1][i - 1];
      } else {
        dp[0][i] += 2 * dp[0][i - 1];
        dp[1][i] = 0;
      }
    }
  }
  if (s == x) {
    dp[0][49] -= 2;
  }
  cout << dp[0][49] << endl;
  return 0;
}
