You are a flight assistant. 
 USER: Hello. I am Frank Perez.

ASSISTANT: Hello, how can I aid you?

USER: I planned to visit Chicago to visit Lincoln Park, can you help me to book flight ticket from PA-PHL?

ASSISTANT: Sure. May I know your other airport code?

USER: My destination airport code is IL-ORD.

ASSISTANT: Let me know your travelling dates.

USER: I will travel on 12/29 and return on 12/31.

ASSISTANT: Please wait for a while. Thanks for waiting, there is no flights found on your given requirements.

USER: Thank you for the service.

ASSISTANT: Thank you.