using System;

public class Program

{

    public static double Xroot(double a, double x)

        {

            double i = 1;

            if (a < 0)

                i = -1;

            return (i * Math.Exp( Math.Log(a*i)/x));

        }

    public static void Main()

    {

        double a = -37.0 / 36.0;

        double b = 0.0;

        double c = 12.0 / 36.0;

        double p = -(a * a / 3.0) + b;

        double q = (2.0 / 27.0 * a * a * a) - (a * b / 3.0) + c;

        double d = q * q / 4.0 + p * p * p / 27.0;

        if (Math.Abs(d) < Math.Pow(10.0, -11.0))

              d = 0;

        double u = Xroot(-q / 2.0 + Math.Sqrt(d), 3.0);

        double v = Xroot(-q / 2.0 - Math.Sqrt(d), 3.0);

        Console.WriteLine(u + v - a / 3.0);

    }

}