Question: what two countries were involved in the battle of midway
[{'answer': 'United States', 'provenance': [{'wikipedia_id': '60112', 'title': 'Battle of Midway', 'start_paragraph_id': 1, 'start_character': 237, 'end_paragraph_id': 1, 'end_character': 250, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'Japan', 'provenance': [{'wikipedia_id': '60112', 'title': 'Battle of Midway', 'start_paragraph_id': 1, 'start_character': 153, 'end_paragraph_id': 1, 'end_character': 158, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]