You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: Please book a ticket from JFK to DEN to attend Film festival.

ASSISTANT: Sure, may I know your travel dates?

USER: My travelling dates are Sept 21 and Sept 23.

ASSISTANT: Do you have any preferences?

USER: I prefer business class.

ASSISTANT: May I know your name?

USER: Sure, I am Elizabeth Parker.

ASSISTANT: Ok, please wait a minute.

USER: Sure.

ASSISTANT: Sorry, there were no flights found on your route.

USER: Ok, no issues. Thank you.

ASSISTANT: Thank you.