You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I aid you at this moment?

USER: I am Frank Hall. Can you please reserve me a  direct flight ticket from Las Vegas to Denver?

ASSISTANT: Sure, Can you please let me know your preferable travel dates?

USER: My trip dates are 12/01 - 12/03.

ASSISTANT: May I know your preferable airport code names for further process?

USER: My airport codes are LAS - DEN.

ASSISTANT: Is there any additional preferences do you have?

USER: I need a normal - cost airline.

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: Sorry, no flights are available in this route as per your requested dates.

USER: No issues, thank you for your information.

ASSISTANT: Thank you for reaching us.