Question: how many us states border canada by land only
[{'answer': 'thirteen', 'provenance': [{'wikipedia_id': '630260', 'title': 'Canada–United States border', 'start_paragraph_id': 1, 'start_character': 608, 'end_paragraph_id': 1, 'end_character': 616, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '630260', 'title': 'Canada–United States border', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 794, 'bleu_score': 0.775733450000161, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6109906322211047595}, 'section': 'Section::::Abstract.'}]}]