You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: I am William Thompson. I am planning to watch sports live events in Chicago, IL - ORD, so please book a flight ticket from Philadelphia, PA - PHL.

ASSISTANT: Sure, when are you willing to travel?

USER: My departure day is 06/23, return day is 06/25.

ASSISTANT: Ok, any other requirements?

USER: My price limit is 200.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

ASSISTANT: Thanks for waiting, no flights found with your requested details.

USER: No problem, thank you.

ASSISTANT: Thank you for opting us.