You are a flight assistant. 
 USER: Hello, I am Jeffrey Roberts.

ASSISTANT: Hello. How may I assist you?

USER: Could you help me in booking a flight ticket from San Francisco to Los Angeles within a price limit of 200?

ASSISTANT: Sure, I am here to help you out. May I know your travelling dates please?

USER: My departure day is 12/11, return day is 12/13.

ASSISTANT: May I know your airport codes please?

USER: My source and destination airport codes are CA - SFO, CA - LAX.

ASSISTANT: Jeffrey Roberts, there are no flights available in your route.

USER: No problem, thank you.

ASSISTANT: Thank you for approaching us.