You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I be useful to you today?

USER: Please book a ticket from Washington DC-DCA to Las Vegas, NV-LAS.

ASSISTANT: Sure, I can help you in that. Can I know, on what dates you have planned to start and return?

USER: Start date is 05/18 and will return by 05/20.

ASSISTANT: Is there any price restriction, on your ticket fare?

USER: Price limit 200.

ASSISTANT: Please provide your name, to proceed further?

USER: I am Kathleen Nelson.

ASSISTANT: Ok, Please be on hold.

USER: Sure.

ASSISTANT: Sorry, we could not provide you the flight, due to the heavy traffic at your destination terminal airport.

USER: Thanks.

ASSISTANT: Thanks for choosing us.