You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Rebecca Clark.

ASSISTANT: What can I do for you Clark?

USER: I'm planning to visit Las Vegas LAS on 09/11, can you please help me in booking a ticket?

ASSISTANT: Sure Rebecca, can I know your nearest airport and return date please?

USER: My return day will be on 09/13. I want to start my journey from IAD.

ASSISTANT: Ok, wait a moment please.

USER: Ok.

ASSISTANT: Sorry for inconvenience, there are no flights as per your request.

USER: That's ok.

ASSISTANT: Thank you for your positive response.

USER: Thank you for your time.

ASSISTANT: You are welcome.