Question: who do the avengers fight in infinity war
[{'answer': 'Thanos', 'provenance': [{'wikipedia_id': '44240443', 'title': 'Avengers: Infinity War', 'start_paragraph_id': 1, 'start_character': 827, 'end_paragraph_id': 1, 'end_character': 833, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '44240443', 'title': 'Avengers: Infinity War', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 927, 'bleu_score': 0.693434844212334, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17396100014788862834}, 'section': 'Section::::Abstract.'}]}]