Question: how many episodes in the viet nam series
[{'answer': '10', 'provenance': [{'wikipedia_id': '54018381', 'title': 'The Vietnam War (TV series)', 'start_paragraph_id': 1, 'start_character': 21, 'end_paragraph_id': 1, 'end_character': 23, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]