class Program
{
    static void Main(string[] args)
    {
        string[] input = Console.ReadLine()!.Split(' ');
        double total = double.Parse(input[0]);
        double count = double.Parse(input[1]);

        double denominator = (total + 1) * count;

        double sum = 0;
        int num = 0;
        for (int i = 0; i < denominator; i++)
        {
            if (i % count == 0)
            {
                num++;
            }
            sum += 1 / denominator * num;
        }

        Console.WriteLine(sum - 1);
    }
}