You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am David White.

ASSISTANT: How may I aid you today?

USER: I am planning to book a ticket from AUS to DCA. Can you please help me out to book a ticket for me?

ASSISTANT: Sure, I am happy to help you with that. Can I know your planned trip dates?

USER: I would like to travel on 07/14 and return back on 07/16.

ASSISTANT: Ok, wait for a minute.

USER: Sure.

ASSISTANT: I regret to say that, there are no flight's available based on your travelling dates.

USER: That's fine.

ASSISTANT: Thank you for reaching us.

USER: Thank you for your information.