class Drawable {
    void draw() {}
}
class Circle extends Drawable {
    void draw() {
        System.out.println("o");
    }
}
public class DrawableList<E extends Drawable> {
    E element;
    DrawableList<E> next;
    void drawAll() {
        element.draw();
        if (next == null) return;
        else next.drawAll();
    }  
}