enum BookType {
  BOOK,
  MAGAZINE
}

class BookOrMagazine {
  public BookType type;
  public String name;
}

class User {
  public String name;
  private List<BookOrMagazine> bookOrMagazines = new ArrayList<BookOrMagazine>();
  public void addBookOrMagazine(BookOrMagazine bookOrMagazine) {
    if (bookOrMagazines.size() >= 3) {
      throw new IllegalArgumentException("на руках у одного человека не может быть одновременно больше 3х наименований книг и/или газет");
    }
    bookOrMagazines.add(bookOrMagazine);
  }
  public void bookCount() {
    int countBook = 0;
    int countMagazine = 0;
    for (BookOrMagazine bookOrMagazine : bookOrMagazines) {
      if (bookOrMagazine.type == BookType.BOOK) {
        countBook += 1;
      }
      if (bookOrMagazine.type == BookType.MAGAZINE) {
        countMagazine += 1;
      }
    }
    System.out.println("на руках у конкретного человека книг - " + countBook);
    System.out.println("на руках у конкретного человека газет - " + countMagazine);
  }
}

class Library {
  public List<User> users = new ArrayList<User>();
}

class Main {
  public static void main(String[] args) {
    BookOrMagazine book1 = new BookOrMagazine();
    book1.type = BookType.BOOK;
    book1.name = "Книга 1";
    User user = new User();
    user.addBookOrMagazine(book1);
    user.bookCount();
  }
}