#include <bits/stdc++.h>
using namespace std;
long long s, x;
bool bitX[40], bitS[40];
long long dp[41][2];
int maxBit;
long long solve(int bit, bool carry) {
  if (bit == maxBit) return !carry;
  if (dp[bit][carry] != -1) return dp[bit][carry];
  long long ans;
  if (bitX[bit]) {
    if (carry) {
      if (bitS[bit])
        ans = 0;
      else
        ans = 2LL * solve(bit + 1, 1);
    } else {
      if (!bitS[bit])
        ans = 0;
      else
        ans = 2LL * solve(bit + 1, 0);
    }
  } else {
    if (carry) {
      if (!bitS[bit])
        ans = 0;
      else
        ans = solve(bit + 1, 0) + solve(bit + 1, 1);
    } else {
      if (bitS[bit])
        ans = 0;
      else
        ans = solve(bit + 1, 0) + solve(bit + 1, 1);
    }
  }
  return dp[bit][carry] = ans;
}
int main() {
  cin >> s >> x;
  long long temp = s, temp2 = x;
  int neg = x == s ? -2 : 0;
  while (temp || temp2) {
    maxBit++;
    temp /= 2;
    temp2 /= 2;
  }
  for (long long i = 0; i < 40; i++) {
    bitX[i] = x % 2;
    x /= 2;
    bitS[i] = s % 2;
    s /= 2;
  }
  memset(dp, -1, sizeof dp);
  long long ans = solve(0, 0);
  cout << ans + neg;
  return 0;
}
