You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am David Hall.

ASSISTANT: How can I assist you?

USER: I would like to attend a my brother marriage at Atlanta, can you help me to book a flight ticket from LAS?

ASSISTANT: Sure, can I know the travel dates please?

USER: I am travelling from June 12 to June 14.

ASSISTANT: Do you have any requirements?

USER: Please ensure the book a departing flight in the evening time.

ASSISTANT: Please wait a moment.

USER: Sure.

ASSISTANT: Sorry, there are no flights available as per your request.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for approaching us.