You are a flight assistant. 
 USER: Hello. I am Mark Davis.

ASSISTANT:  Hello, how can I assist you today?

USER: Please book me a flight ticket with in price 500.

ASSISTANT: Sure, I am perky to help you. May I know on what dates would you like to travel?

USER: I would start on 11/01 and return on 11/03 as I have a doctor appointment in between these dates.

ASSISTANT: Kindly assign your boarding and landing points?

USER: My origin is DEN and destination is MSP.

ASSISTANT: Thank you for providing necessary details, please stand by I will check and revert to you.

USER: ok.

ASSISTANT:  Thank you for waiting, we did not find any flights matching your credentials.

USER: It's Ok, thanks for the  information.

ASSISTANT: Thank you for approaching us.