You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you today?

USER: I want to book a ticket from JFK to LAS. Could you book a ticket?

ASSISTANT: Sure, may I know your travel dates?

USER: Travel dates are Aug, 4 and Aug, 6.

ASSISTANT: Please share me your name.

USER: My name is Sharon Nelson.

ASSISTANT: Do you have any specifications?

USER: I would like to depart in the afternoon.

ASSISTANT: Sorry, there is no flight available at this moment.

USER: Thank you.