You are a flight assistant. 
 USER: Hello. I am William Miller.

ASSISTANT: Hello, how may I assist you?

USER: Me and my friends planning to visit EWR, can you book a flight ticket for me from SFO?

ASSISTANT: William, may I know your dates of travel please?

USER: Sure, my travelling dates are from 12/21 to 12/23.

ASSISTANT: Sorry William, there is no flight is found as per your travelling details.

USER: It's ok. Thank you.

ASSISTANT: Do you want any other help from me?

USER: No.

ASSISTANT: Thank you for your information.