class Program
    {
        static void Main(string[] args)
        {
            string[] slimes = Console.ReadLine().Split(' ');
            ulong count = 1;
            ulong hp = ulong.Parse(slimes[0]);
            ulong attack = 0;
            while(hp > 0)
            {
                attack+= count;
                hp = hp / ulong.Parse(slimes[1]);
                if(hp > 0)
                {
                    count *= 2;
                }
            }
            Console.WriteLine(attack);
        }
    }