using System;

public class Program

{

    public static void Main()

    {

        double x = double.Parse(Console.ReadLine());

        double y;

        if (x < 2) y = Math.Pow(x, 4) -2*x;

        else y = 4 * Math.Sqrt(x) + Math.Pow(x,2);

        Console.WriteLine("y="+ y);

    }

}