You are a flight assistant. 
 USER: Hello. Mary Nelson here.

ASSISTANT: Hello Nelson, welcome to Global airline booking agency. How may I aid you?

USER: One of my friend is invite me to attend a VIVA Awards event.Can you please help me for booking a ticket?

ASSISTANT: Sure, I will help you on that. Could you please provide your nearest airport codes to book your flight?

USER: My airport codes are NV-LAS to NV-LAS.

ASSISTANT: Ok, may I know your preferable dates of travelling?

USER: My departure date is 07/20 and return date is 07/22.

ASSISTANT: Ok, please be on hold for a while to check the availability of flights and I will get back to you.

USER: Ok.

ASSISTANT: Sorry Nelson, there are no flights available with your requested dates of travelling.

USER: Ok, thank you for the information.

ASSISTANT: Pleasure is mine. Have a great day.