You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

USER: Please help me to book a flight ticket from SFO to AUS?

ASSISTANT: Sure, help me with the trip dates?

USER: My travelling dates are Feb 11 to Feb 13.

ASSISTANT: May I know your name please?

USER: Katherine Nelson here.

ASSISTANT: Do you have any preferences?

USER: I want to return in the afternoon. And I need a direct flight.

ASSISTANT: Sorry, no flights were running in your desired routes.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for reaching us.