You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, do you need any help from us?

USER: I am looking for a flight from IAD to OAK, can you please help me in booking?

ASSISTANT: Ok, could you please share your trip dates?

USER: My travelling dates are Oct 16 and Oct 18.

ASSISTANT: Ok, could I have your name please?

USER: My name is Scott Nelson.

ASSISTANT: Ok, do you need direct or connecting flight?

USER: I need a direct flight.

ASSISTANT: Ok, do you have any other specifications?

USER: No, thanks for asking.

ASSISTANT: Sorry, there is no flight on your requested travelling dates.

USER: That's ok, thank you for checking.

ASSISTANT: You are welcome.