You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Margaret Clark.

ASSISTANT: How can I assist you today?

USER: Can you help me to book a flight from LAS to DEN?

ASSISTANT: Sure, I can help you with that. May I know your planned travel dates please?

USER: My travelling dates are 09/29 and return on 10/01.

ASSISTANT: Ok, do you prefer to travel in economy or business class?

USER: I need a business class ticket.

ASSISTANT: Sorry to inform you that there are no business class tickets available on those dates.

USER: No problem, thank you for your information.