instruction: how much is a FIRST class ticket from BOSTON to SAN FRANCISCO
response: SELECT DISTINCT fare.fare_id FROM airport_service AS AIRPORT_SERVICE_0, airport_service AS AIRPORT_SERVICE_1, city AS CITY_0, city AS CITY_1, fare, fare_basis, flight, flight_fare WHERE CITY_0.city_code = AIRPORT_SERVICE_0.city_code AND CITY_0.city_name = 'BOSTON' AND CITY_1.city_code = AIRPORT_SERVICE_1.city_code AND CITY_1.city_name = 'SAN FRANCISCO' AND fare_basis.class_type = 'FIRST' AND fare.fare_basis_code = fare_basis.fare_basis_code AND flight_fare.fare_id = fare.fare_id AND flight.flight_id = flight_fare.flight_id AND flight.from_airport = AIRPORT_SERVICE_0.airport_code AND flight.to_airport = AIRPORT_SERVICE_1.airport_code