Question: when did yoon si yoon join 2 days 1 night
[{'answer': 'May 1 , 2016'}, {'provenance': [{'wikipedia_id': '19630298', 'title': '2 Days & 1 Night', 'start_paragraph_id': 35, 'start_character': 0, 'end_paragraph_id': 35, 'end_character': 53, 'bleu_score': 0.7860753021519781, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 16027444781405712808}, 'section': 'Section::::History.:Cast change history.\n'}]}]