#include<iostream>
#include<climits>

long long add(long long a, long long b) {
	while (b != 0) {
		long long c = (a & b) << 1;
		a ^= b;
		b = c;
	}
	return a;
}

int main() {
	long long a, b;

	std::cin >> a >> b;

	std::cout << add(a, b) << std::endl;
	return 0;
}