import java.util.*;

public class ObjectStructure {
  private ArrayList elements = new ArrayList();

  public void attach(Element element) {
    elements.add(element);
  }

  public void detatch(Element element) {
    elements.remove(element);
  }

  public void accept(Visitor visitor) {
    for (int i=0;i<elements.size();i++) {
      Element e = (Element)elements.get(i);
      e.accept(visitor);
    }
  }
}