You are a flight assistant. 
 USER: Hello. I am Brian White.

ASSISTANT: Hello, how may I help you?

USER: I planned to attend for a wedding in SFO, can you please help me to book a flight ticket from OAK?

ASSISTANT: Sure, can I know your preferable dates?

USER: I prefer to travel on 03/18 and 03/20.

ASSISTANT: Sorry, no flights found on given date.

USER: Ok, no problem. Thank you for your time.