Tell the number of flights that landed at Lake Charles Regional Airport on 2018/8/15.
landed at refers to DEST; Lake Charles Regional Airport refers to Description = 'Lake Charles, LA: Lake Charles Regional'; on 2018/8/15 refers to FL_DATE = '2018/8/15';
SELECT COUNT(T1.Code) FROM Airports AS T1 INNER JOIN Airlines AS T2 ON T1.Code = T2.DEST WHERE T2.FL_DATE = '2018/8/15' AND T1.Description = 'Lake Charles, LA: Lake Charles Regional'