using System;

​

public class Program

{

    static double S(int k, int n)

    {

        if (k <= 0 || n <= 0)

        {

            return -1;

        }

        else

        {

            return Math.Sqrt(n) + S(k, n - 1);

        }

    }

​

    public static void Main()

    {

        Console.WriteLine("Vuvedi k i n (polozitelni cisla): ");

        int n = int.Parse(Console.ReadLine());

        int k = int.Parse(Console.ReadLine());

        double res = S(k, n);

        if (res == -1)

        {

            Console.WriteLine("Vuvedi polozitelni cisla!!!");

        }

        else

        {

            Console.WriteLine(res);

        }

    }

}