You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: I want to meet my brother on his birthday, can you please help me to book my flight ticket from LAX to OAK?

ASSISTANT: Sure, please provide me your travelling dates to search a flight.

USER: Sure, I would like to depart on 12/27 and return on 12/29.

ASSISTANT: May I know your name to proceed further?

USER: Sure, my name is Benjamin Smith.

ASSISTANT: I could not find any flight with your travelling dates.

USER: Oh! That's fine. Anyway, thank you.

ASSISTANT: My pleasure.