You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: Can you please book me a flight ticket from DEN to DCA?

ASSISTANT: Please provide your journey dates?

USER: My journey dates are from Nov 8th to Nov 10th.

ASSISTANT: Do you have any preference?

USER: I prefer an economy class to travel. I want a single connection.

ASSISTANT: May I know your name?

USER: I am Stephen Hall.

ASSISTANT: Sorry, currently there is no flight for your requirement.

USER: No problem.

ASSISTANT: Thanks.

USER: Thank you.