You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am William Collins.

ASSISTANT: How can I help you today?

USER: I want to attend an event in San Francisco. Can you book a ticket from EWR to SFO?

ASSISTANT: Sure, I will help you with this. Can you please provide your travel dates to proceed further?

USER: I want to travel in the flight on 04/25 and 04/27.

ASSISTANT: Wait a moment please.

USER: Ok.

ASSISTANT: William Collins, there is no flight service available on your provided dates on this route.

USER: That's ok. Anyways, thank you for your help.

ASSISTANT: Thank you for choosing us.