i would like to book a train ticket , please .
user
where are your departure and destination sites ?
assistant
i am looking for a train that is leaving on friday after 21:45 .
user
there are 46 trains operating on friday at that time . can i get your destination to narrow down the results ?
assistant
yes . i would like to go to leicester . what trains are available ?
user
i have 2 trains going from cambridge to leicester . 1 leaving at 22:21 and 1 leaving at 23:21 . would you like to book 1 of these ?
assistant
i will go with the earlier departure , and i would like 2 seats please . i will also need a reference number .