using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Ener x ");

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

        double y;

        if(x < 3 )

        {

          y = x*x;

          Console.WriteLine(y);

        }

        else if(x >= 3 && x <= 15)

        {

            y = x+1;

            Console.WriteLine(y);

        }

        else if (x > 15)

        { y = x-9;

            Console.WriteLine(y);

        }

    }

}