You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: I want to attend a food festival at Las Vegas. Can you book a flight ticket from OAK to LAS?

ASSISTANT: Sure, can I have your name please?

USER: David Lewis here.

ASSISTANT: Thank you, let me know your travel dates?

USER: Sept, 21 and Sept, 23 are my planned travel dates.

ASSISTANT: Do you have any connection limit?

USER: No, I need direct flight.

ASSISTANT: Any class preference?

USER: Yes, I prefer to economy class.

ASSISTANT: Sorry David Lewis, no flights found with your given details.

USER: That's ok, no problem. Thank you.

ASSISTANT: Thank you for reaching us.