class Program
    {
            private static double Rec(double i, double n)
            {
                return i < n ? Math.Sqrt(i + Rec(++i, n)) : Math.Sqrt(i);
            }

            static void Main(string[] args)
            {
                Console.Write("Enter N:");
                var n = Convert.ToInt32(Console.ReadLine());
                Console.WriteLine("Result : " + n / Rec(1, n));
                
            }
        }