Question: when did the united states join united nations
[{'answer': 'October 24 , 1945', 'provenance': [{'wikipedia_id': '335057', 'title': 'United States and the United Nations', 'start_paragraph_id': 9, 'start_character': 53, 'end_paragraph_id': 9, 'end_character': 70, 'bleu_score': 1.0, 'section': 'Section::::Role in establishing the UN.\n'}]}]