You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you for the day?

USER: I am planning to book a ticket from DEN to DCA. Can you please help me out?

ASSISTANT: When you are willing to travel?

USER: I am planning to travel on Nov 17 and return back on Nov 19.

ASSISTANT: Do you have any class preference?

USER: No, I am ok with any class.

ASSISTANT: Do you have any connection limit?

USER: Yes, I am looking for a connecting flight.

ASSISTANT: May, I know your good name?

USER: I am Daniel Phillips.

ASSISTANT: Do you have any other specifications?

USER: No.

ASSISTANT: Sorry, we found no flights on your given dates.

USER: That's fine, thank you for your service.

ASSISTANT: Thank you for reaching us.