Question: who was the president of pakistan in 1958
[{'answer': 'Iskander Mirza', 'provenance': [{'wikipedia_id': '461863', 'title': 'List of Presidents of Pakistan', 'start_paragraph_id': 2, 'start_character': 208, 'end_paragraph_id': 2, 'end_character': 222, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'Ayub Khan', 'provenance': [{'wikipedia_id': '461863', 'title': 'List of Presidents of Pakistan', 'start_paragraph_id': 3, 'start_character': 317, 'end_paragraph_id': 3, 'end_character': 326, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]