// yukicoder: No.415 ぴょん
// 2019.4.16 bal4u

#include <stdio.h>

int gcd(int a, int b)
{
	int r;
	while (b != 0) r = a % b, a = b, b = r;
	return a;
}

int main()
{
	int N, D, g, ans;

	scanf("%d%d", &N, &D);
	if (N == D) ans = 0;
	else if (N % D == 0) ans = N / D - 1;
	else {
		g = gcd(N, D);
		ans = N / g - 1;
	}
	printf("%d\n", ans);
	return 0;
}