You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I serve you at this moment?

USER: I am Carol Roberts. I am planning to attend Tennis competition in Los Angeles LAX from DEN. Can you find a flight ticket for me?

ASSISTANT: Sure, I will help you. Please send your travelling dates.

USER: Ok, my planned trip dates are on Sept 25 and return on Sept 27.

ASSISTANT: Noted. Do you have any preferences?

USER: Yes, I need a business class.

ASSISTANT: Sorry, there is no flight available matching your requiement.

USER: Ok, not an problem. Thank you for your information.

ASSISTANT: You are welcome, have a nice day.