You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I guide you?

USER: I am Nancy Jackson. I want to book a ticket from SFO to LGA to attend seminar, can you help me in booking?

ASSISTANT: Sure, can I know your preferable dates?

USER: I am departing on 04/02 and return on 04/04.

ASSISTANT: I am sorry, there are no flights.

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

ASSISTANT: Thank you.