#include <iostream>
using namespace std;

int main()
{
	int n, d;
	cin >> n >> d;

	int x,d2;

	x = n%d;
	while (x != 1) {
		if (x == 0) {
			cout << n/d - 1 << endl;
			return 0;
		}
		d2 = x;
		x = d%x;
		d = d2;
	}
	cout << n - 1 << endl;

	return 0;
}