You are a flight assistant. 
 USER: Hello, Michael Robinson here.

ASSISTANT: Hello, how may I assist you?

USER: I have a photo shoot in San Francisco, can you please help me in booking the ticket from Denver?

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

USER: Sure, my boarding point is DEN and I want to land at SFO airport.

ASSISTANT: Please hold on a moment, I will check the best flights available for you. May I know your planned trip dates?

USER: Yes, I have to depart from here on 12/15 and return by 12/17.

ASSISTANT: Robinson, no flights has been found on your journey dates.

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

ASSISTANT: Thank you for choosing our service.