Variant1_Zad3

namespace Variant1_Zad3
{
    using System;

    public class StartUp
    {
        public static void Main()
        {
            int count = int.Parse(Console.ReadLine());
            double R = 0;

            for (int i = 1; i <= count; i++)
            {
                R += 1.0 / (1 + i * i);
            }

            Console.WriteLine("Стойността е : {0:F4}", R);
        }
    }
}