You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I am Helen Mitchell. I would like to book a ticket to Denver, can you please book me a ticket from DFW to DEN?

ASSISTANT: May I know your desired travel dates please?

USER: I am travelling on these dates Aug 10th and 12th. I have a connection limit 0.

ASSISTANT: Do you have any class preference?

USER: My price limit is 200.

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

USER: Ok no problem, thank you for your services.

ASSISTANT: Thank you for opting us.