Question: what is the first book of pretty little liars
[{'answer': 'Pretty Little Liars', 'provenance': [{'wikipedia_id': '12012861', 'title': 'Pretty Little Liars (book series)', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 19, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]