#include <iostream>

typedef long long ll;

ll n, d;

ll gcd(ll a, ll b) {
	if (b == 0)return a;
	return gcd(b, a % b);
}

int main() {
	std::cin >> n >> d;
	std::cout << n / gcd(n, d) - 1 << std::endl;

	return 0;
}