answer: #Person1# helps #Person2# buy a first-class single ticket of flight BW159 to Sydney.
documents: #Person1#: Good morning, sir. What can I do for you?
  #Person2#: I want to buy a ticket to Sydney tomorrow.
  #Person1#: Right now fight BW159 is the only one available, it is a non-direct one.
  #Person2#: What's the exact information?
  #Person1#: It departs at 4:40 pm tomorrow and arrives in Sydney at 10:20 am. the next morning by way of Melboume.
  #Person2#: How long is the layover in Melboume?
  #Person1#: About 1 hour. Would you buy it?
  #Person2#: Yes. I want a first class single ticket.