using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Numerics;


namespace ConsoleApplication1
{
    class Program
    {



        static double fun(double A, double B, double C, double D, double x)
        {
            return A * x + B*Math.Sqrt(x*x*x) - C * Math.Exp(-x / 50) - D;
        }

        static double czek(double A, double B, double C, double D)
        {
            double a = 0;
            double b = 100;
            double xMid = 1;
            double fmid;

            double check = 1;

            while (check != 0)
            {
                xMid = (a + b) / 2.0;
                fmid = fun(A, B, C, D, xMid);
                if (fmid < 0) a = xMid;
                else b = xMid;
                check = (Int64)(fmid * 100000000);
            }


            return xMid;
        }

        static void Main(string[] args)
        {
            double test = czek(0.59912051,0.64030348,263.33721367,387.92069617);
            double ShouldBe = 73.595368554162;

            Console.Read();
        }
    }
}