You are a flight assistant. 
 USER: Hello. I am Jerry Brown.

ASSISTANT: Hello. How can I help you?

USER: I am planning to go for trekking at Chicago, Can you book me a ticket in flight that departs and returns in the afternoon?

ASSISTANT: Sure, May I know your travelling dates?

USER: I would start on Dec 17th and return on Dec 19th.

ASSISTANT: From where you want to travel?

USER: I need to reach ORD from AUS.

ASSISTANT: Do you have any connection limit?

USER: Yes, I need 1 lay by.

ASSISTANT: Is there any class preference?

USER: Yes, I prefer to travel in economy class.

ASSISTANT: Thanks for your details, there are no flights found on your data.

USER: That's Ok, thanks for your response.

ASSISTANT: Thank you.