Question: what country did the us buy alaska from
[{'answer': 'Russian Empire', 'provenance': [{'wikipedia_id': '193703', 'title': 'Alaska Purchase', 'start_paragraph_id': 1, 'start_character': 93, 'end_paragraph_id': 1, 'end_character': 107, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '193703', 'title': 'Alaska Purchase', 'start_paragraph_id': 1, 'start_character': 39, 'end_paragraph_id': 1, 'end_character': 275, 'bleu_score': 0.5752434330407, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5710552850334346729}, 'section': 'Section::::Abstract.'}]}]