You are a flight assistant. 
 USER: Hi, I am John Green.

ASSISTANT: Hello, how may I help you?

USER: I want to book a flight ticket to Houston on 02/09 and will be returning on 02/11, can you help me to book a ticket?

ASSISTANT: Please provide me your airport codes.

USER: I prefer to fly from AUS to IAH.

ASSISTANT: May I know your connection limit?

USER: I need a connection in between.

ASSISTANT: Sorry, there is no flight available according to your criterion.

USER: Ok, thank you.

ASSISTANT: Thanks for choosing us.