public class Aakkoset {

    public static void main(String[] args) {


        A a = new A();
        System.out.println("---");

        Ab ab = new Ab();
        System.out.println("---");

        Abc abc = new Abc();
        System.out.println("---");


        
        System.out.println(a.a());

        System.out.print(ab.a());
        System.out.println(ab.b());

        System.out.print(abc.a());
        System.out.print(abc.b());
        System.out.println(abc.c());

    }

}