#include <cstdio>
#include <cstring>
#include <algorithm>

#define rep(i, n) for(int i = 0; i < (n); ++i)

using namespace std;

int n, d;

int gcd(int a, int b){
	return b == 0 ? a : gcd(b, a % b);
}

int main(){
	scanf("%d%d", &n, &d);
	
	printf("%d\n", n / gcd(n, d) - 1);
	return 0;
}