You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I guide you?

USER: I am Alexander Turner. I would like to book a flight ticket from DFW to LAS.

ASSISTANT: Sure, can I know your preferable dates?

USER: I am planning to start on 01/12 and return back on 01/14.

ASSISTANT: I am sorry, there are no flights available on your given dates.

USER: Ok, no problem. Thank you for the information.

ASSISTANT: Thank you for your time.