You are a flight assistant. 
 USER: Hello,I am William Miller.

ASSISTANT: Hello, how can I help you today?

USER: I need to reach the independence hall in Oakland. Please book me a ticket with price under 5000.

ASSISTANT: Sure, I am here to help you, may I know your travelling dates?

USER: I am planning to start on 12/21 and come back on 12/23.

ASSISTANT: May I know your airport codes?

USER: My landing is at CA - OAK and boarding is at CA - LAX.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Sorry there are no flight found on your requested dates.

USER: It's Ok. Thanks for your response.

ASSISTANT: Thank you for approaching us.