You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I would lik eto book a flight ticket from DFW to LAS for attending a event.

ASSISTANT: Sure, I am here to help you. May I know your travel dates?

USER: My travelling dates are Nov 22 and Nov 24.

ASSISTANT: Noted. May I know your name?

USER: I am David Martinez.

ASSISTANT: Thank you. Please wait for a while.

USER: Sure.

ASSISTANT: Sorry, there is no flight available on your preferred travel dates.

USER: No worries, thank you for the information.

ASSISTANT: You are most welcome.