#include <bits/stdc++.h>
using namespace std;
long long sum, Xor;
long long dp[65][2][2][2];
long long solve(int indx, int carry, bool x, bool y, long long xx = 0,
                long long yy = 0) {
  if (indx == 63) {
    return (x && y && carry == 0);
  }
  long long &res = dp[indx][carry][x][y];
  if (res != -1) return res;
  res = 0;
  for (int i = 0; i < 2; ++i) {
    for (int j = 0; j < 2; ++j) {
      int a = ((Xor >> indx) & 1), b = ((sum >> indx) & 1);
      if ((i ^ j) == a && (i + j + carry) % 2 == b) {
        long long _x = xx, _y = yy;
        if (i) _x |= (1 << indx);
        if (j) _y |= (1 << indx);
        res += solve(indx + 1, (i + j + carry) / 2, x | i, y | j, _x, _y);
      }
    }
  }
  return res;
}
int main() {
  cin >> sum >> Xor;
  memset(dp, -1, sizeof dp);
  cout << solve(0, 0, 0, 0) << endl;
  return 0;
}
