#include <bits/stdc++.h>
using namespace std;
long long int table[64][2];
int main() {
  long long int s, x;
  cin >> s >> x;
  int l = 0;
  while ((1ll << l) <= s || (1ll << l) <= x) l++;
  table[l][0] = 1;
  for (int i = l - 1; i >= 0; i--)
    for (int c = 0; c < 2; c++)
      for (int j = 0; j < 2; j++)
        for (int k = 0; k < 2; k++)
          if ((c + j + k) % 2 == ((s >> i) & 1) && (j ^ k) == ((x >> i) & 1))
            table[i][c] += table[i + 1][(c + j + k) / 2];
  cout << table[0][0] - (s == x) * 2 << '\n';
}
