Код 2 лаба

class Program
{
    static void Main()
    {
        var check  = new Wating();
        var call = new Call();
        var end = new Talk();
        call.AnswerCall();
        end.EndCall();
    }
}

class Check
{
    public int number;
    public double balance;
    public void BuyMinutes()
    {
        balance++;
    }
}

 class Stateline : Check
{
    public static bool LineIsBusy = false;
    public static void Update() 
        {
            if (LineIsBusy is true)
            {
                LineIsBusy = false;
            }
            else
            {
                LineIsBusy = true;
            }
        }
}

class Wating : Stateline
{
    public void Call()
    {
        Stateline.Update();
    }
}

class Talk : Stateline
{
    public void EndCall()
    {
        Stateline.Update();
    }
}

class Call : Stateline
{
    public void AnswerCall()
    {
        Stateline.Update();
    }
    public void EndCall()
    {
        Stateline.Update();
    }
}