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

class Program
{
	static int[] I32ParseList(string[] strs)
	{
		List<int> result = new List<int>();
		foreach (string s in strs)
		{
			result.Add(Int32.Parse(s));
		}
		return result.ToArray();
	}

	static int Saidaikouyakusuu(int a, int b)
	{
		int n = a % b;

		while (n != 0)
		{
			a = b;
			b = n;
			n = a % b;
		}

		return b;
	}

	static int Pyon(int n, int k)
	{
		if (n - k == 1 || k == 1)
		{
			return n - 1;
		}

		// 最大公約数を調べる
		int r = Saidaikouyakusuu(n, k);
			
		if (r == 1)
		{
			return n - 1;
		}

		return n / r - 1;
	}

	static void Main(string[] args)
	{
		int[] nk = I32ParseList(Console.ReadLine().Split(' '));

		int cnt = Pyon(nk[0], nk[1]);

		Console.WriteLine(cnt.ToString());
	}
}