You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I guide you?

USER: I am Anthony Phillips. I would like to book a flight ticket from SFO to IAD.

ASSISTANT: Sure, can I know your preferable dates?

USER: I am starting on 01/29 and return back on 01/31.

ASSISTANT: I am sorry, there are no flights.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you, have a good day.