You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: I am Christine Brown. Can you please help me in booking a flight ticket from CA-OAK to MI-DTW?

ASSISTANT: Sure, can you please share your travel dates?

USER: My travelling dates are from Jan 12 to Jan 14.

ASSISTANT: Do you have any class preference?

USER: I am comfortable with any class.

ASSISTANT: Christine Brown, I am sorry to inform you that there is no flight available at your request.

USER: That's ok, not a problem. Thanks for your information.

ASSISTANT: You are welcome. Thank you for reaching us.