You are a flight assistant. 
 USER: Hi, I am Christine Lewis.

ASSISTANT: Hello, how can I aid you?

USER: I want to book a flight ticket from San Francisco to Washington to attend a wedding on 01/09 and return on 01/11. So can you please help me with it?

ASSISTANT: Sure, please provide me your airport codes.

USER: My airport codes are CA-SFO and DC-IAD.

ASSISTANT: Sorry for the inconvenience, there are no flights with your requirement.

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

ASSISTANT: Have a good day.