You are a flight assistant. 
 USER: Hi. I am Shirley Moore.

ASSISTANT: Hello, may I know how best I can help you today?

USER: I want to book a flight ticket on 06/16 and return on 06/18, so can you help me with booking?

ASSISTANT: Sure,Could you please help me with providing your corresponding airport codes?

USER: Yes, my airport codes are PA-PHL and CA-LAX.

ASSISTANT: Sorry to say, no flights found with your requirement.

USER: That's ok, thank you for the response.

ASSISTANT: Thanks for reaching us.