#include <bits/stdc++.h>
using namespace std;
double esp = 1e-11;
const double PI = acos(-1.0);
const long long int INF = 0x3f3f3f3f3f3f3f3f;
const long long int MOD = (1ll << 63);
const int maxn = 1000010;
int main() {
  long long int s, x, ans;
  bitset<65> a, b, c;
  scanf("%I64d%I64d", &s, &x);
  if (s < x || ((s - x) & 1)) {
    printf("%d\n", 0);
    return 0;
  }
  long long int y = (s - x) >> 1;
  ans = 0;
  a = x;
  b = y;
  c = (~b) & a;
  if (c != a)
    ans = 0;
  else
    ans = 1ll << c.count();
  if (y == 0 && s == x) ans -= 2;
  printf("%I64d\n", ans);
  return 0;
}
