Question: how much land did the us gain after the mexican american war
[{'answer': '900,000 square miles'}, {'provenance': [{'wikipedia_id': '21073732', 'title': 'Mexican–American War', 'start_paragraph_id': 182, 'start_character': 0, 'end_paragraph_id': 182, 'end_character': 217, 'bleu_score': 0.563936084020608, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 15093615846776604834}, 'section': 'Section::::Results.:Altered territories.\n'}]}]