You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you?

USER: I am Stephen Evans, want to travel from DEN to LAS. Please help me in booking my ticket.

ASSISTANT: Sure, please share your trip dates.

USER: My travelling dates are from 10/03 to 10/05.

ASSISTANT: Do you have any specifications?

USER: Yes, my return time will be in the afternoon.

ASSISTANT: Do you have any other preferences?

USER: No.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Sorry Stephen Evans, no flights are available in the afternoon.

USER: It's ok, thank you.

ASSISTANT: Thank you for choosing us.