#include<iostream>
#include<string>
#include<algorithm>

long long gcd(long long n, long long k) {
	if (k == 0) return n;
	return gcd(k, n % k);
}

int main() {
	long long n, k;

	std::cin >> n >> k;

	long long ggg = gcd(n, k);

	if (ggg == 1) {
		std::cout << n - 1 << std::endl;
	} else {
		std::cout << n / k - 1<< std::endl;
	}

	return 0;
}