You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you?

USER: Please book a flight ticket from DCA to DEN.

ASSISTANT: Sure, I am here to help you out. May I know your travel dates please?

USER: My trip dates are 01/18 and 01/20.

ASSISTANT: Can you please share your connection limit?

USER: I need a connecting flight.

ASSISTANT: Do you have any other specifications?

USER: No.

ASSISTANT: May I know your name please?

USER: Melissa Carter here.

ASSISTANT: Melissa Carter, there are no flights available in your route with your preference.

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

ASSISTANT: Thank you for choosing us.