Among the flights operated by American Airlines Inc. on 2018/8/1, how many of them were cancelled?
American Airlines Inc. refers to Description = 'American Airlines Inc.: AA'; on 2018/8/1 refers to FL_DATE = '2018/8/1'; cancelled refers to CANCELLED = 1;
SELECT SUM(CASE WHEN T2.CANCELLED = 1 THEN 1 ELSE 0 END) AS count FROM Airports AS T1 INNER JOIN Airlines AS T2 ON T1.Code = T2.ORIGIN INNER JOIN `Air Carriers` AS T3 ON T2.OP_CARRIER_AIRLINE_ID = T3.Code WHERE T2.FL_DATE = '2018/8/1' AND T3.Description = 'American Airlines Inc.: AA'