#include <bits/stdc++.h>
using namespace std;
const int INF = 0x3f3f3f3f;
const long long LINF = 0x3f3f3f3f3f3f3f3f;
const int LMAX = 50;
long long s, x;
long long dp[LMAX][2] = {0};
void clear() { memset(dp, 0, sizeof(dp)); }
void solve() {
  dp[0][0] = 1;
  for (int i = 1; i < LMAX; i++) {
    int bx = x >> i - 1 & 1, bs = s >> i - 1 & 1;
    if (bx == 1 && bs == 1) dp[i][1] = 0, dp[i][0] = 2 * dp[i - 1][0];
    if (bx == 1 && bs == 0) dp[i][1] = 2 * dp[i - 1][1], dp[i][0] = 0;
    if (bx == 0 && bs == 0) dp[i][1] = dp[i - 1][0], dp[i][0] = dp[i - 1][0];
    if (bx == 0 && bs == 1) dp[i][1] = dp[i - 1][1], dp[i][0] = dp[i - 1][1];
  }
  long long res = dp[LMAX - 1][0] - (s == x ? 2 : 0);
  printf("%lld\n", res);
}
int main() {
  while (scanf("%lld%lld", &s, &x) == 2) {
    clear();
    solve();
    return 0;
  }
  return 0;
}
