You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. Is there any help that I can assist you?

USER: Can you help me to book a flight ticket from DCA to SEA?

ASSISTANT: Sure, I am glad to help you and can I know your preferable dates?

USER: My travel dates are Aug 17 and Aug 19.

ASSISTANT: Is there any lay by that you need in your journey?

USER: I prefer direct flight for this trip.

ASSISTANT: Please let me know if any other requirements.

USER: I would like to prefer business class flight ticket.

ASSISTANT: Can I know your name please?

USER: I am Nicholas Taylor.

ASSISTANT: Please allow me a moment.

USER: Sure.

ASSISTANT: Thank you for waiting, there is no flight obtained on your travel dates to book a flight ticket.

USER: No problem, thank you for the information.

ASSISTANT: You are most welcome and have a nice day.