You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I am Christopher Walker. I want to book a ticket from OAK to JFK to attend seminar, can you help me in booking?

ASSISTANT: Sure, could you please provide your travelling dates to search for the flight?

USER: I am departing on Sep 01 and return on Sep 03.

ASSISTANT: Do you prefer any halt in between journey?

USER: I need a direct flight.

ASSISTANT: Sorry to say, no flight is available for you.

USER: That's ok, thank you for your information.

ASSISTANT: Welcome.