You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: My name is Steven Miller. I would like to travel from DCA to SFO, could you help me out?

ASSISTANT: May I know your trip dates?

USER: My preferable dates are from 12/03 to 12/05.

ASSISTANT: Sorry, there is no flight available as per your request.

USER: That's ok. Thank you, have a good day.

ASSISTANT: Most welcome.