You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, what kind of help assistance you are looking for?

USER: I want to book a flight ticket from DEN to OAK. Could you help me in booking?

ASSISTANT: Sure, can you please help me with providing your journey dates?

USER: My travelling dates are from Dec 18-20.

ASSISTANT: In which class you wish to travel?

USER: I am comfort with any.

ASSISTANT: Please mention your connection limit for this trip.

USER: I prefer for single connection limit.

ASSISTANT: May I know your name please?

USER: Susan Evans here.

ASSISTANT:  Do you have any more specifications?

USER: My return time should be in the evening.

ASSISTANT: Ok, please wait for a while.

USER: Ok.

ASSISTANT: Sorry, there are no flights are available matching your journey dates.

USER: That's ok, no problem. Thank you.

ASSISTANT: Thank you for availing us.