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

ASSISTANT: Hello, how can I help you?

USER: I have a plan to visit Redwood regional park at Oakland, please book a flight ticket within price 500.

ASSISTANT: Sure, may I know your planned journey dates?

USER: My planned travelling dates are from 01/29 to 01/31.

ASSISTANT: Please share your airport codes.

USER: I need a direct flight so that I want to fly from DFW to OAK.

ASSISTANT: Ok, please wait for a moment.

USER: O"k. Ok.

ASSISTANT: Sorry, no flights found with your given details.

USER: No issues. Thank you.

ASSISTANT: Thank you for opting us.