}

  @Override
  public int size() {
    return elements.size();
  }

  @Override
  public boolean contains(@Nullable Object o) {
    try {
      return o != null && unsafeBinarySearch(o) >= 0;
    } catch (ClassCastException e) {
      return false;
    }
  }

  @Override
  public boolean containsAll(Collection<?> targets) {