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

namespace PrintDeckOfCards
{
    class Program
    {
        static void Main()
        {
            int N = int.Parse(Console.ReadLine());
            int x = int.Parse(Console.ReadLine());
            double sum = 1;
            int factoriel = 1;

            for (int i = 1; i <= N; i++)
            {
                factoriel *= i;
                sum += factoriel / Math.Pow(x, i);
            }
            Console.WriteLine($"{sum:F5}");
        }
    }
}