Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Surabaya to Denver as you normally would.
SUB and DEN are unique codes to identify airports used in the aviation industry. They are defined by IATA (International Air Transport Association) and are commonly called IATA codes. SUB to DEN refers to a flight route from Surabaya Juanda Airport to Denver Intl Airport.