You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: Can you help me in booking my flight ticket from DTW to EWR?

ASSISTANT: Sure, can you share your journey dates?

USER: My journey dates will be Dec 18th to Dec 20th.

ASSISTANT: Do you have any preferences?

USER: I need a business class.

ASSISTANT: May I know your name?

USER: I am James Adams.

ASSISTANT: Sorry, there is no flight on your given dates.

USER: Its ok, thank you.

ASSISTANT: Thank you for opting us.