using System;

public class Hello
{
    static void Main()
    {

        string[] line = Console.ReadLine().Trim().Split(' ');
        var h = long.Parse(line[0]);
        var a = long.Parse(line[1]);
        getAns(h, a);
    }
    static void getAns(long h, long a)
    {
        var ans = 1L;
        var p = 1L;
        while (h > 1)
        {
            h /= a;
            p *= 2;
            ans += p;
        }
        Console.WriteLine(ans);
    }
}