Question: who is the first president of nigeria after independent
[{'answer': 'Nnamdi Azikiwe', 'provenance': [{'wikipedia_id': '24110210', 'title': 'List of heads of state of Nigeria', 'start_paragraph_id': 6, 'start_character': 708, 'end_paragraph_id': 6, 'end_character': 722, 'bleu_score': 1.0, 'section': 'Section::::Monarch (1960–1963).:Governor-General.\n'}]}]