Return the number of United Airlines flights leaving from AHD Airport.
SELECT count(*) FROM AIRLINES AS T1 JOIN FLIGHTS AS T2 ON T2.Airline  =  T1.uid WHERE T1.Airline  =  "United Airlines" AND T2.SourceAirport  =  "AHD"
SELECT count(*) FROM AIRLINES AS T1 JOIN FLIGHTS AS T2 ON T2.Airline  =  T1.uid WHERE T1.Airline  =  "United Airlines" AND T2.SourceAirport  =  "AHD"
[{'count(*)': 0}]