You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I be at your service?

USER: I am Katherine Baker. Can you please book a flight ticket from ATL to DCA?

ASSISTANT: Sure, may I know your depart and return dates?

USER: Sure, I need to travel on dates of Nov 26 and Nov 28.

ASSISTANT: Do you prefer either economy or business class?

USER: I am ok with any class.

ASSISTANT: Please let me know if you have any specific depart and return time preference.

USER: Yes, I would like to depart in the evening time only.

ASSISTANT: Sure, please wait for a while.

USER: Sure, take your time.

ASSISTANT: Sorry, we don't have any flight which departs in the evening.

USER: Oh! It is sad to hear. Anyway, thank you for your time.

ASSISTANT: Thank you for contacting us.

USER: Most welcome.