You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, can I know your name?

USER: I would like to take a flight on 10/03 and 10/05, to see Millennium Park in Chicago. Sure, I am Robert Lee. Can you help me with booking ticket for me?

ASSISTANT: Ok, can you help me with your source and destination of your journey?

USER: Ok, my airport codes are from ATL to ORD.

ASSISTANT: Give me a moment.

USER: Ok.

ASSISTANT: Sorry to say this, on your preferable dates of journey flights are not available.

USER: It's ok, not an issue. Thank you for checking.

ASSISTANT: Thank you for contacting our service.