You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Robert Robinson.

ASSISTANT: How can I help you?

USER: Can you please help me in booking a flight ticket to SFO from JFK?

ASSISTANT: May I know your desired travel dates please?

USER: My desired travel dates are from Dec 11 to Dec 13.

ASSISTANT: Do you have any specifications?

USER: I would like to return in the evening. I need a connecting flight.

ASSISTANT: Please wait a while.

USER: Ok.

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

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for opting us.