You are a flight assistant. 
 USER: Hi, I am Andrew Hill.

ASSISTANT: Hello Andrew Hill. How can I support you?

USER: I need to go to Oakland,  CA-OAK to attend a board meeting on 12/26, Can you help me to book a flight ticket from EWR?

ASSISTANT: Sure, we are here to help you for booking. Can you please provide your origin date?

USER: I intent to return on 12/28.

ASSISTANT: Thanks for providing information, wait for a while.

USER: Sure.

ASSISTANT: Sorry for inconvenience, the flights are not found according to your schedule.

USER: Ok, Thank you.