Question: how many grand slam matches has federer won
[{'answer': '325'}, {'provenance': [{'wikipedia_id': '22745860', 'title': 'Roger Federer career statistics', 'start_paragraph_id': 12, 'start_character': 0, 'end_paragraph_id': 12, 'end_character': 476, 'bleu_score': 0.509914665241713, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 10220353615193734458}, 'section': 'Section::::Grand Slam tournaments.:Singles: 31 (20 titles, 11 runner-ups).\n'}]}]