ค้นหาชื่อสนามกีฬาที่นักว่ายน้ำเคยไปมากที่สุด
Find the names of stadiums that the most swimmers have been to.
record = pd.DataFrame(columns=['event_id']); stadium = pd.DataFrame(columns=['name', 'id']); event = pd.DataFrame(columns=['stadium_id', 'id'])
stadium[stadium['id'] == event[event['id'].isin(record['event_id'])]['stadium_id'].value_counts().idxmax()]['name']