You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I want to book a flight ticket from Los Angeles LAX to Denver DEN. Can you find a flight ticket for me?

ASSISTANT: Sure, May I know your travelling dates?

USER: Ok, my planned trip dates are on Oct 15 and return on Oct 17.

ASSISTANT: Do you have any class preference?

USER: Yes, I need an economy class.

ASSISTANT: Is there any other preferences?

USER: Yes, I want to return in the evening time.

ASSISTANT: May I know your name?

USER: Yes, I am Samantha Young.

ASSISTANT: Thanks for your details, there are no flights found on your data.

USER: Ok, not an issue. Thank you for your help,.

ASSISTANT: Thank you.