You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I want to attend a Seminar in New York. Can you please help me for booking the flight ticket?

ASSISTANT: May I know your desired travel dates please?

USER: My travelling dates are Sep 02 and Sep 04.

ASSISTANT: Can I know your preferred airport codes please?

USER: My airport codes are DEN and EWR.

ASSISTANT: Do you have any specifications?

USER: I would prefer nonstop flight.

ASSISTANT: May I know your name please?

USER: My name is Stephen Walker.

ASSISTANT: Sorry to say, there is no flight on your desired travel dates.

USER: Anyway, thanks for the information.

ASSISTANT: Thank you for opting us.