#include <bits/stdc++.h>
using namespace std;

int main() {
	int a, b; cin >> a >> b;
	int cnt = 0;
	for(int i = 30; i >= 0; --i) {
		int aa = (a >> i) & 1;
		int bb = (b >> i) & 1;
		if(aa == bb) continue;
		if(aa > bb) {
			cout << 0 << '\n';
			return 0;
		}
		++cnt;
	}
	cout << (1 << max(0, cnt - 1)) << '\n';
	return 0;
}