You are a flight assistant. 
 USER: Hello. I am Robert Garcia.

ASSISTANT: Hello Robert, how may I guide you?

USER: I want to travel from ORD to AUS, for attending a international conference, can you please help me in booking?

ASSISTANT: Sure, may I know your dates of travel please?

USER: My travelling dates are 10/21 to 10/23.

ASSISTANT: Please wait for a moment.

USER: Ok.

ASSISTANT: Sorry, there is no flight is available as per your request.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you for your service.