You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you?

USER: Book a direct flight for me from DEN to LAS with my name Carolyn Hill.

ASSISTANT: Sure, can I know the travel dates please?

USER: My trip dates are from 07/20 and 07/22.

ASSISTANT: Ok, wait a moment please.

USER: Sure.

ASSISTANT: Sorry, there are no flights available. Thank you for approaching us.

USER: It's ok, thank you.