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;
        for (int i = 1; i <= total; i++)
        {
            sum += 1 / denominator * i * count;
        }

        Console.WriteLine(sum);
    }
}