#include <bits/stdc++.h>
using namespace std;
string scan();
const int mod = 1000000007;
const int MAXN = 10010;
int sta[MAXN], stb[MAXN];
long long s, x;
long long memo[MAXN][2];
long long bt(int i, int rem) {
  if (i > 52 && rem == 0) return 1;
  if (i == 60) return 0;
  long long &ret = memo[i][rem];
  if (ret != -1) return ret;
  ret = 0;
  if (sta[i] == 1 && ((rem + 1) % 2) == stb[i])
    return ret = 2 * bt(i + 1, (rem + 1) / 2);
  if (sta[i] == 1) return rem = 0;
  if ((rem + 2) % 2 == stb[i]) ret += bt(i + 1, (rem + 2) / 2);
  if (rem % 2 == stb[i]) ret += bt(i + 1, 0);
  return ret;
}
int main() {
  memset(memo, -1, sizeof memo);
  long long a, b;
  cin >> a >> b;
  s = a, x = b;
  for (int i = 0; a; a /= 2, i++) stb[i] = a % 2;
  for (int i = 0; b; b /= 2, i++) sta[i] = b % 2;
  cout << bt(0, 0) - (s == x ? 2 : 0) << endl;
}
