You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

USER: I want to travel from AUS to IAD. Can you help me to book a flight ticket?

ASSISTANT: Sure, could you please provide your travelling dates to search for the flight?

USER: I want to fly in the flight on Oct 17 and Oct 19.

ASSISTANT: Do you have any requirements?

USER: I prefer to travel in business class.

ASSISTANT: Can I have your name?

USER: I am William White.

ASSISTANT: Do you have any time concern?

USER: No.

ASSISTANT: Sorry to say, no flight is available for you as per your requests.

USER: That's ok. Anyways, thank you for your help.

ASSISTANT: Thank you for reaching us.