You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello,.

USER: My name is Ashley Walker.

ASSISTANT: How may I help you?

USER: I want to book a flight ticket with a price limit of 500 for visiting a Liberty Bell in Philadelphia.

ASSISTANT: Sure, may I know your travelling dates?

USER: My departure day is 06/17, return day is 06/19.

ASSISTANT: Can you please provide your journey codes?

USER: My source and destination airport codes are CA-OAK, PA-PHL. Connections limit is one.

ASSISTANT: Please wait for a minute.

USER: Ok.

ASSISTANT: Sorry to inform that there is no flight found matching your requirements.

USER: No problem, thanks for your service.

ASSISTANT: Thank you for reaching us.