Question: when was the first warrior cats book published
[{'answer': 'January 21 , 2003', 'provenance': [{'wikipedia_id': '1886892', 'title': 'Warriors (novel series)', 'start_paragraph_id': 18, 'start_character': 158, 'end_paragraph_id': 18, 'end_character': 175, 'bleu_score': 1.0, 'section': 'Section::::Series.:"Warriors: The Prophecies Begin".\n'}]}, {'provenance': [{'wikipedia_id': '1886892', 'title': 'Warriors (novel series)', 'start_paragraph_id': 18, 'start_character': 0, 'end_paragraph_id': 18, 'end_character': 754, 'bleu_score': 0.9187832324426811, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 146872128395501623}, 'section': 'Section::::Series.:"Warriors: The Prophecies Begin".\n'}]}]