You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you?

USER: I need you to book a flight ticket from AUS to IAH. Please help me.

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

USER: August 18 and 20 are my planned travelling dates.

ASSISTANT: Do you have any class preferences?

USER: Nothing to state.

ASSISTANT: Can I know your name?

USER: Steven Carter.

ASSISTANT: Sorry to say, no flight is available for you.

USER: That's ok. Thank you.

ASSISTANT: Thank you for reaching us.