Question: when did russia stop using the julian calendar
[{'answer': 'February 1918', 'provenance': [{'wikipedia_id': '180861', 'title': 'Soviet calendar', 'start_paragraph_id': 1, 'start_character': 258, 'end_paragraph_id': 1, 'end_character': 271, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]