You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, what can I do for you?

USER: I want to attend Detroit.Can you please help for booking the flight ticket from MI-DTW to DC-DCA?

ASSISTANT: Sure, may I know your required dates?

USER: The required dates are from 05/13 to 05/15.

ASSISTANT: Sure, give me a moment.

USER: Ok.

ASSISTANT: May I know your name?

USER: Sure, my name is Brian Roberts.

ASSISTANT: Sorry Roberts, there is no flight with your requirements.

USER: Ok, It's fine. Thank you for your information.

ASSISTANT: You are welcome.