You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I need to book a ticket from EWR to OAK. Could you book a ticket?

ASSISTANT: Sure, can you share your journey dates?

USER: Departure is Dec, 18 and return date is Dec, 20.

ASSISTANT: Do you have any preferences?

USER: I prefer to travel in business class.

ASSISTANT: May I know your name?

USER: My name is Joshua Davis.

ASSISTANT: Sorry, there is no flight on your given dates.

USER: Thank you.

ASSISTANT: Thank you for reaching us.