You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: Could you please book a ticket from New York to Las Vegas.

ASSISTANT: Sure, I will help you in booking the ticket. May I know your travelling dates please?

USER: Departure is on Dec, 3 and return will be Dec, 5.

ASSISTANT: Please share me your source and destination codes.

USER: My airport codes are EWR and LAS.

ASSISTANT: Do you have any other specifications?

USER: I prefer to travel in economy class.

ASSISTANT: Please help me with your name for booking.

USER: I am Kevin Evans.

ASSISTANT: Sorry for this inconvenience, I could not find any flight with your requirements.

USER: Thanks.