#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
#include<sstream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<climits>
#include<cmath>
#include<string>
#include<vector>
#include<set>
#include<map>
#include<queue>
#include<numeric>
#include<functional>
#include<algorithm>
#include<bitset>
#include<tuple>
#include<unordered_set>
#include<unordered_map>
#include<random>
#include<array>
#include<cassert>
using namespace std;
#define INF (1<<29)
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(v) v.begin(),v.end()
#define uniq(v) v.erase(unique(all(v)),v.end())




int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);

	int a, b;
	cin >> a >> b;

	int cnt = 0;

	rep(i, 31) {
		int x = a >> i & 1, y = b >> i & 1;


		if (x == 1 && y == 0) {
			cout << 0 << endl;
			return 0;
		}
		if (x == 0 && y == 1) {
			cnt++;
		}
	}

	if (cnt == 0)cout << 1 << endl;
	cout << (1 << cnt - 1) << endl;

	return 0;
}