You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I guide you?

USER: I am Benjamin Phillips,. I want to book a ticket from DCA to EWR.

ASSISTANT: Sure, can I know your preferable dates?

USER: My preferable dates are from 02/24 to 02/26.

ASSISTANT: I am sorry, there are no flights available.

USER: That's ok, no problem.

ASSISTANT: Thank you, have a good day.

USER: Thank you for helping me.