You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Stephen Wright.

ASSISTANT: How may I serve you today?

USER: I would like to visit San Francisco. Can you help me for booking a flight ticket from AUS to SFO?

ASSISTANT: Sure, let me know your travel dates please?

USER: My travelling dates are June 12 and June 14.

ASSISTANT: Do you need a stopover?

USER: I need a direct flight in my journey.

ASSISTANT: Do you have any class preference?

USER: Any class is fine for me.

ASSISTANT: When do you want to depart and return on?

USER: My departure time is evening.

ASSISTANT: Do you have any other specifications?

USER: No.

ASSISTANT: Sorry to say that, there are no flights available on the routes of your journey.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for availing us.

USER: Welcome.