You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Can you please help me to book a flight from SFO to AUS?

ASSISTANT: Sure. Do you have any specifications?

USER: I need a connecting flight with an economy class in normal-cost airline.

ASSISTANT: Could you provide your travelling dates?

USER: Sure, I want to travel on Dec 8 and need to return on Dec 10.

ASSISTANT: Is there any class preference?

USER: I already mentioned above.

ASSISTANT: Ok. Can I know your name?

USER: I am Justin Green.

ASSISTANT: Found ticket with United airlines for price 100. Shall I book a ticket?

USER: Ok, please book this flight.

ASSISTANT: Ticket is booked in an economy class having flight number 1019.

USER: Thank you.

ASSISTANT: Thank you.