/**
 * A Strategy that discards the hung up phone and all calls
 * directly added to this conversation by that phone.
 * Any calls indirectly added are still retained.
 */
public class Strategy2 implements Strategy {
  
  private SearchableStack<Phone> ss; 
  
  /**
   * A fixed capacity conversation, backed by an ArraySearchableStack.
   * @param capacity  the maximum size of this conversation
   */   
  public Strategy2(int capacity) {
    ss = new ArraySearchableStack<Phone>(capacity); 
  }
  
  /**
   * A conversation of unlimited capacity, backed by an ArrayListSearchableStack.
   */ 
  public Strategy2() {
    ss = new ArrayListSearchableStack<Phone>();
  }
  
  // CONTINUE FROM HERE
}