You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. In which way I can aid you at this moment?

USER: I am Brian Allen. I want to book a flight ticket from DEN to AUS. Could you help me in booking?

ASSISTANT: Sure, I will help you in booking flight ticket.

USER: Thank you.

ASSISTANT: Can you please mention your preferable travel dates for further process?

USER: My travelling dates are from 04/28 to 04/30.

ASSISTANT: Ok, please hold on a moment, I will check flight availability in this route.

USER: Ok.

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

USER: That's ok, no problem. Thank you.

ASSISTANT: Thank you for reaching us.