A customer books a flight to Seoul.

— Yes, I need a round-trip, first-class ticket to Seoul, leaving on the 13th and returning on the 20th.
— Yes sir. Let's see... we have two flights on the 13th. The first is non-stop and leaves at 7 a.m. The second leaves at 11 a.m. with a two-hour layover in Tokyo. And for the return flight on the 20th, the non-stop leaves at 8 a.m., and the layover flight leaves at noon.
— I'd prefer the non-stop, if it's not much more expensive.
— The non-stop is $500; and the flight with the Tokyo layover is $475.