#include <bits/stdc++.h>
using namespace std;
const double kEps = 10e-8;
const int kMax = 1000;
const int kInf = 1 << 30;
long long s, x;
int msb;
long long dp[64][2][2][2];
long long f(int p, int c, int a, int b) {
  if (p > msb) {
    return (c == 0 && a == 1 && b == 1) ? 1 : 0;
  }
  long long& ans = dp[p][c][a][b];
  if (ans != -1) {
    return ans;
  }
  ans = 0;
  int sb = (s & (1ll << p)) != 0;
  int xb = (x & (1ll << p)) != 0;
  if (xb == 0) {
    int v = c;
    if (v % 2 == sb) {
      ans += f(p + 1, v / 2, a, b);
    }
    v = 2 + c;
    if (v % 2 == sb) {
      ans += f(p + 1, v / 2, 1, 1);
    }
  } else {
    int v = 1 + c;
    if (v % 2 == sb) {
      ans += f(p + 1, v / 2, 1, b);
      ans += f(p + 1, v / 2, a, 1);
    }
  }
  return ans;
}
int main() {
  cin >> s >> x;
  msb = 0;
  for (int i = 0; i < 63; i++) {
    if (s & (1ll << i)) {
      msb = i;
    }
    if (x & (1ll << i)) {
      msb = i;
    }
  }
  memset(dp, -1, sizeof dp);
  cout << f(0, 0, 0, 0);
  return EXIT_SUCCESS;
}
