#include <cstdio>
using namespace std;
 
int gcd(int a, int b) {
	if (b == 0) return a;
	return gcd(b, a%b);
}

int main() {
	int n, d;
	scanf("%d %d", &n, &d);
	printf("%d\n", (n/gcd(n, d) - 1));
}