public static void main(String[] args) {
	try (Scanner sc = new Scanner(System.in);) {
		int l = sc.nextInt();
		int r = sc.nextInt();
		System.out.println(allOne(l ^ r));
	}
}
	
public static int allOne(int i) {
	i |= (i >>  1);
	i |= (i >>  2);
	i |= (i >>  4);
	i |= (i >>  8);
	i |= (i >> 16);
	return i;
}