cout << "Prosze podaj ID ksiazki" << endl;
                cin >> a;

                if (a <= c && a > 0)
                {

                    while ((p->ID != a) && p->next)
                    {
                        p = p->next;
                        w = w->next;
                    }


                    if (p->ID == a)
                    {
                        book *w = head;
                        int i = p->ID;

                        while(w->next)
                        {
                            w = w->next;
                            w->ID = i;
                            i++;
                        }