Question: how many ouran high school books are there
[{'answer': 'eighteen tankōbon volumes', 'provenance': [{'wikipedia_id': '7059328', 'title': 'List of Ouran High School Host Club chapters', 'start_paragraph_id': 2, 'start_character': 164, 'end_paragraph_id': 2, 'end_character': 189, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '7059328', 'title': 'List of Ouran High School Host Club chapters', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 765, 'bleu_score': 0.9843125095516201, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14500139500719267877}, 'section': 'Section::::Abstract.'}]}]