You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, do you need any help from us?

USER: I need to buy a plane ticket from AUS to IAD. Can you help me?

ASSISTANT: Sure, could you please share your departure and arrival day?

USER: I will start on Dec 15th and return on Dec 17th.

ASSISTANT: Ok, could I have your name please?

USER: I am Susan Clark.

ASSISTANT: Ok, do you need direct or connecting flight?

USER: I need 1 stop over within my route.

ASSISTANT: Ok, do you have any other specifications?

USER: Yes, My depart time must be in the afternoon and return time must be in the morning.

ASSISTANT: Sorry, there is no flight on your requested travelling dates.

USER: That's alright, thanks for your assistance.

ASSISTANT: You are welcome, have a great day.