You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: My name is Sharon Hill. I want to book a flight ticket with price limit 200.

ASSISTANT: OK, may I know your journey details please?

USER: My departure day is 12/25, return day is 12/27.

ASSISTANT: Sure, may I know your airport codes please?

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

ASSISTANT: Ok please wait I will get back to you.

USER: Ok.

ASSISTANT: Thanks for your waiting, we have not found any flights with your requested dates.

USER: No issues, thanks for your service.

ASSISTANT: Thanks for contacting us.