using System;

public class Program

{

    static double DevFunc1(double x)

    {

        return 4 * Math.Pow(x,3) - 2 * x;

    }

    static double DevFunc2(double x)

    {

        return 3 * Math.Pow(x,2) - 1;

    }

    public static void Main()

    {

        double x0 = 1;

        double eps = 0.01;

        Console.WriteLine("C = " + Newton(x0,eps));

    }

    public static double Newton(double x0, double eps)

    {

        double x1;

        x1 = x0 - DevFunc1(x0)/ DevFunc2(x0);

        if(Math.Abs(x1 - x0) > eps)

            Newton(x1,eps);

        if(x1 <= 0)

            return x1;

        else

            throw new Exception("Не найден экстремум");

    }

}