You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Andrew Hill.

ASSISTANT: How can I help you?

USER: I am going for a family trip to Charlotte, please book a ticket from LAS to CLT.

ASSISTANT: Sure, please provide the travelling dates?

USER: My preferred dates are 12/26 and 12/28. Price should not exceed 500.

ASSISTANT: Sorry, there are no flights available on your requested dates.

USER: It's ok, thank you for your time.

ASSISTANT: Thank you for reaching us.