instruction: what are the early weekday flights from SAN FRANCISCO to PITTSBURGH
response: SELECT DISTINCT flight.flight_id FROM airport_service AS AIRPORT_SERVICE_0, airport_service AS AIRPORT_SERVICE_1, city AS CITY_0, city AS CITY_1, days AS DAYS_0, days AS DAYS_1, days AS DAYS_2, days AS DAYS_3, days AS DAYS_4, flight WHERE ((((((DAYS_3.day_name = 'THURSDAY' AND DAYS_4.day_name = 'FRIDAY' AND flight.flight_days = DAYS_3.days_code AND flight.flight_days = DAYS_4.days_code) AND DAYS_2.day_name = 'WEDNESDAY' AND flight.flight_days = DAYS_2.days_code) AND DAYS_1.day_name = 'TUESDAY' AND flight.flight_days = DAYS_1.days_code) AND DAYS_0.day_name = 'MONDAY' AND flight.flight_days = DAYS_0.days_code) AND flight.departure_time < 1000) AND CITY_1.city_code = AIRPORT_SERVICE_1.city_code AND CITY_1.city_name = 'PITTSBURGH' AND flight.to_airport = AIRPORT_SERVICE_1.airport_code) AND CITY_0.city_code = AIRPORT_SERVICE_0.city_code AND CITY_0.city_name = 'SAN FRANCISCO' AND flight.from_airport = AIRPORT_SERVICE_0.airport_code