using System;
using System.Collections.Generic;
using System.Linq;

public class Test
{
	public static void Main()
	{
		var nd = Console.ReadLine()
					.Split(' ')
					.Select(x => int.Parse(x))
					.ToList();
		
		Console.WriteLine(nd[0] / GCD(nd[0], nd[1]) - 1);
	}
	
	public static int GCD(int a, int b)
	{
		if(a % b == 0) return b;
		else return GCD(b, a % b);
	}
	
}