You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am John White.

ASSISTANT: How can I help you?

USER: Can you book a flight ticket from OAK to SFO?

ASSISTANT: Sure, May I know your travelling dates?

USER: Sept, 28 and Sept, 30 are my travel dates.

ASSISTANT: Do you have any connection limit?

USER: I need single connection.

ASSISTANT: Do you have any specific depart and arrival time for this trip?

USER: My return time should be at afternoon.

ASSISTANT: Thanks for your details, there are no flights found on your data.

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

ASSISTANT: Thank you.