You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Mark Mitchell.

ASSISTANT: How can I help you?

USER: I need to book a flight ticket from JFK to ORD, Can you please help me for booking?

ASSISTANT: Let me know your travelling dates.

USER: I would like to travel on 12/26 to return on 12/28.

ASSISTANT: Do you have any preference?

USER: I need a business class with return time is evening.

ASSISTANT: Sorry, no flights found for your travelling dates.

USER: Ok, no problem.

ASSISTANT: Thank you.

USER: Thanks for your information.