#include <bits/stdc++.h>
using namespace std;
long long s, x;
long long dp[66][2];
long long solve(int pos, int carry) {
  if (pos == 50) {
    return (carry == 0);
  }
  if (dp[pos][carry] != -1) return dp[pos][carry];
  long long answer = 0;
  for (int b1 = 0; b1 <= 1; b1++)
    for (int b2 = 0; b2 <= 1; b2++) {
      if ((b1 ^ b2) != ((x >> pos) & 1)) continue;
      if ((b1 + b2 + carry) % 2 != ((s >> pos) & 1)) continue;
      answer += solve(pos + 1, (b1 + b2 + carry) / 2);
    }
  return dp[pos][carry] = answer;
}
long long solvebrute() {
  long long ct = 0;
  for (int a = 1; a <= s; a++)
    for (int b = 1; b <= s - a; b++)
      if (a + b == s && (a ^ b) == x) ct++;
  return ct;
}
int main() {
  cin >> s >> x;
  for (int i = 0; i <= 60; i++) dp[i][0] = dp[i][1] = -1;
  long long answer = solve(0, 0);
  if (s == x) {
    answer -= 2;
  }
  cout << answer << endl;
}
