show me the cheapest one way flights from dallas to san francisco leaving dallas after 4 pm
O O O B-cost_relative B-round_trip I-round_trip O O B-fromloc.city_name O B-toloc.city_name I-toloc.city_name O B-fromloc.city_name B-depart_time.time_relative B-depart_time.time I-depart_time.time