import java.util.Scanner;

class Main{
	public static long gcd(long x,long y) {
		long r;
		if(y>x) {
			r=x;
			x=y;
			y=r;
		}
		while(y>0) {
			r=x%y;
			x=y;
			y=r;
		}
		return x;
	}
	
	public static long lcm(long x,long y) {
		return x*y/gcd(x,y);
	}
	
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		long n=sc.nextLong(),d=sc.nextLong();
		sc.close();
		System.out.print(lcm(n,d)/d-1);
	}
}