You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: My name is Gregory Robinson.

ASSISTANT: Ok.

USER: I want to book a flight ticket with a price limit of 500 for attending a client meeting. My departure day is 12/07, return day is 12/09.

ASSISTANT: Sure. Please wait for a while.

USER: My source and destinations are CA-OAK, CA-SFO.

ASSISTANT: May I know your airport abbreviates? Please wait for a minute, I will check and get back to you.

USER: Ok.

ASSISTANT: There is a UA 1001 airline with price of 100 which matches your requirements. Shall I proceed with that?

USER: Yes, please.

ASSISTANT: Your booking has been confirmed. Thank you for approaching us.

USER: Thanks for your service.