You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I support you?

USER: Patrick King here. I want to book a flight ticket from DCA to DEN. Can you help me in that?

ASSISTANT: Sure, we are here to help you. May I know your trip dates?

USER: Thank you. My trip dates are June 17 to 19.

ASSISTANT: Do you need any halt in your journey?

USER: I need halt.

ASSISTANT: Is there any class preference?

USER: No.

ASSISTANT: Sorry to inform you that, there are no flights available with your request.

USER: Ok, not an issue. Thank you.

ASSISTANT: Thank you for reaching us.