You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: I need to book a ticket from DTW to OAK. Could you book a ticket?

ASSISTANT: Sure, tell me your travel dates please?

USER: Departure is on June, 5 and return date is June, 7.

ASSISTANT: Do you have any preferences?

USER: Depart time should be in the evening.

ASSISTANT: Ok, may I know your name please?

USER: My name is Stephen Harris.

ASSISTANT: Wait for a moment please.

USER: Ok.

ASSISTANT: Thanks for your time. Sorry to inform you that there are no flights in the evening time.

USER: Thanks.