round trip fares from denver to philadelphia under 1000 dollars and pittsburgh to philadelphia under 1000 dollars
B-round_trip I-round_trip O O B-fromloc.city_name O B-toloc.city_name B-cost_relative B-fare_amount I-fare_amount O B-fromloc.city_name O B-toloc.city_name B-cost_relative B-fare_amount I-fare_amount