#include <bits/stdc++.h>
using namespace std;
int brute(int s, int x) {
  int ans = 0;
  for (int i = 1; i <= s; ++i)
    for (int j = 1; j <= s; ++j)
      if (i + j == s && (i ^ j) == x) ++ans;
  return ans;
}
long long ways0(long long s, long long x) {
  if (s == x) return 2;
  return 0;
}
long long solve(long long s, long long x) {
  long long dp[60][2] = {};
  if (s % 2 != x % 2) {
    return 0;
  }
  if (x & (1LL << 0)) {
    dp[0][0] = 2;
  } else {
    dp[0][0] = 1;
    dp[0][1] = 1;
  }
  for (int i = 1; i < 60; ++i) {
    if (x & (1LL << i)) {
      if (s & (1LL << i)) {
        dp[i][0] += 2 * dp[i - 1][0];
      } else {
        dp[i][1] += 2 * dp[i - 1][1];
      }
    } else {
      if (s & (1LL << i)) {
        dp[i][0] += dp[i - 1][1];
        dp[i][1] += dp[i - 1][1];
      } else {
        dp[i][0] += dp[i - 1][0];
        dp[i][1] += dp[i - 1][0];
      }
    }
  }
  return dp[59][0] - ways0(s, x);
}
int main() {
  long long s, x;
  cin >> s >> x;
  cout << solve(s, x) << '\n';
}
