You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you?

USER: I am planning to book a flight ticket to DCA from DEN, can you please help me out?

ASSISTANT: Sure, Can I have your trip dates?

USER: Sure, my trip dates are Nov 19 and Nov 21.

ASSISTANT: Do you need any connection limit?

USER: I prefer direct flight.

ASSISTANT: Is there any other specifications?

USER: No.

ASSISTANT: May I know your name?

USER: My name is Christopher Gonzalez.

ASSISTANT: There are no flights available on your routes.

USER: It's ok, thank you for the information.

ASSISTANT: Thank you for choosing us.