You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I am Paul Thomas. I want to book a ticket from DTW to DEN to attend seminar, can you help me?

ASSISTANT: May I know your desired travel dates please?

USER: I am departing on 01/28 and return on 01/30.

ASSISTANT: Sorry to say, there is no flight on your desired travel dates.

USER: That's ok, thank you for your information.

ASSISTANT: Thank you for opting us.