You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: My name is Richard Lewis. I want to book a flight ticket with a price limit of 500 for visiting a Fox Theatre in Atlanta.

ASSISTANT: Ok, may I know your journey dates to proceed further?

USER: My departure day is 02/16, return day is 02/18.

ASSISTANT: Please share your journey codes.

USER: My source and destination airport codes are CO-DEN, GA-ATL.

ASSISTANT: Thank you, sorry to inform no flights found matching your details.

USER: No problem, thanks for your service.

ASSISTANT: Have a nice day.