instruction: show me the shortest flight from BOSTON to DENVER which arrives in DENVER wednesday before 1200
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, date_day, days, flight WHERE ((((((flight.arrival_time < flight.departure_time) AND date_day.day_number = 23 AND date_day.month_number = 4 AND date_day.year = 1991 AND days.day_name = date_day.day_name AND flight.flight_days = days.days_code) OR (date_day.day_number = 23 AND date_day.month_number = 4 AND date_day.year = 1991 AND days.day_name = date_day.day_name AND flight.flight_days = days.days_code AND NOT (flight.arrival_time < flight.departure_time))) AND flight.arrival_time < 1200) AND CITY_1.city_code = AIRPORT_SERVICE_1.city_code AND CITY_1.city_name = 'DENVER' AND flight.to_airport = AIRPORT_SERVICE_1.airport_code) AND CITY_0.city_code = AIRPORT_SERVICE_0.city_code AND CITY_0.city_name = 'BOSTON' AND flight.from_airport = AIRPORT_SERVICE_0.airport_code) AND flight.time_elapsed = (SELECT MIN(FLIGHTalias1.time_elapsed) FROM airport_service AS AIRPORT_SERVICEalias2, airport_service AS AIRPORT_SERVICEalias3, city AS CITYalias2, city AS CITYalias3, date_day AS DATE_DAYalias1, days AS DAYSalias1, flight AS FLIGHTalias1 WHERE (((((FLIGHTalias1.arrival_time < FLIGHTalias1.departure_time) AND DATE_DAYalias1.day_number = 23 AND DATE_DAYalias1.month_number = 4 AND DATE_DAYalias1.year = 1991 AND DAYSalias1.day_name = DATE_DAYalias1.day_name AND FLIGHTalias1.flight_days = DAYSalias1.days_code) OR (DATE_DAYalias1.day_number = 23 AND DATE_DAYalias1.month_number = 4 AND DATE_DAYalias1.year = 1991 AND DAYSalias1.day_name = DATE_DAYalias1.day_name AND FLIGHTalias1.flight_days = DAYSalias1.days_code AND NOT (FLIGHTalias1.arrival_time < FLIGHTalias1.departure_time))) AND FLIGHTalias1.arrival_time < 1200) AND CITYalias3.city_code = AIRPORT_SERVICEalias3.city_code AND CITYalias3.city_name = 'DENVER' AND FLIGHTalias1.to_airport = AIRPORT_SERVICEalias3.airport_code) AND CITYalias2.city_code = AIRPORT_SERVICEalias2.city_code AND CITYalias2.city_name = 'BOSTON' AND FLIGHTalias1.from_airport = AIRPORT_SERVICEalias2.airport_code)