using System;

namespace Yukicoder
{
    public class Program
    {
        public static void Main()
        {
            var line = Console.ReadLine().Split();
            int n = int.Parse(line[0]);
            int d = int.Parse(line[1]);

            int[] circle = new int[n];
            int cur = 0;
            int cnt = 0;
            circle[0] = -1;

            while (true)
            {
                cur += d;
                cur %= n;
                if (circle[cur] == 0)
                {
                    cnt++;
                    circle[cur] = -1;
                }else
                {
                    break;
                }
            }
            Console.WriteLine(cnt);
        }
    }
}