You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: My name is Margaret Wilson. I want to visit Denver for my sister's birthday, could you help me in booking the ticket?

ASSISTANT: Sure, please tell me your origin and destination airport codes along with travelling dates?

USER: It's from CLT to DEN. The dates of travel are from 07/08 to 07/10.

ASSISTANT: I'm sorry, there are no flights available on your requested locations.

USER: That's ok. Thank you for your time.

ASSISTANT: Thank you, have a nice day.