#include <iostream>
#include <set>

int n, d;
std::set<int> s;
int cur, cnt;

int main() {
	std::cin >> n >> d;
	
	if (d == 1)std::cout << n << std::endl;
	else if (d == n - 1)std::cout << n << std::endl;
	else {
		while (s.find(cur) == s.end()) {
			s.insert(cur);
			cur = (cur + d) % n;
			++cnt;
		}

		std::cout << cnt - 1 << std::endl;
	}

	return 0;
}