You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

USER: I am Nancy Roberts. Can you please help me in booking a flight ticket from AZ-PHX to CO-DEN?

ASSISTANT: Sure, may I know your trip dates?

USER: My travelling dates are from Oct 07 to Oct 09.

ASSISTANT: Wait a minute.

USER: Sure.

ASSISTANT: There are no flights available.

USER: That's ok, not a problem. Thank you.

ASSISTANT: Thank you for reaching us.