Question: who has held chief minister office for longest period of time
[{'answer': 'Pawan Kumar Chamling', 'provenance': [{'wikipedia_id': '1509671', 'title': 'Pawan Kumar Chamling', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 20, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '1509671', 'title': 'Pawan Kumar Chamling', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 237, 'bleu_score': 0.583496388476139, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3846318486203365338}, 'section': 'Section::::Abstract.'}]}]