You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: Dennis Johnson here. I'm planning to visit Austin, can you please book a ticket from Denver?

ASSISTANT: Sure, I will help you. May I know your nearest airport codes please?

USER: Sure, my source and destination airport codes are DEN and AUS.

ASSISTANT: May I know your planned travel dates please?

USER: Yes, my planned departure and return travel dates are 14th and 16th of December.

ASSISTANT: Can I know your class preference?

USER: Any class is ok for me.

ASSISTANT: Do you need a connecting flight?

USER: Well, I'm ok with either direct or single connected flight.

ASSISTANT: May I know your departure and arrival timings?

USER: I want to depart on the afternoon, I don't have any specifications in arrival timings.

ASSISTANT: Dennis Johnson, no flights has been found on your planned travel dates.

USER: Oh! That's ok, thank you for giving the information anyways.

ASSISTANT: Thank you for approaching us.