using System;

namespace _3
{
    class Program
    {
        static void Main(string[] args)
        {
            double sum, i, eps = 0.000000001, sl;
            sum = 0;
            i = 1;
            sl = 1 / (i * i);
            while (sl >= eps)
            {
                sum += sl;
                i++;
                sl = 1 / (i * i);
            }
            Console.WriteLine("Сумма ряда = " + sum);
            Console.ReadLine();
        }
    }
}