Question: who was president when yellowstone became a national park
[{'answer': 'Ulysses S. Grant', 'provenance': [{'wikipedia_id': '34340', 'title': 'Yellowstone National Park', 'start_paragraph_id': 1, 'start_character': 168, 'end_paragraph_id': 1, 'end_character': 184, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '34340', 'title': 'Yellowstone National Park', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 595, 'bleu_score': 0.905605488957526, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 4204004316758333453}, 'section': 'Section::::Abstract.'}]}]