You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how can I help you?

USER: I want to make a flight reservation to attend my niece birthday in Las Vegas. Can you book a flight ticket?

ASSISTANT: Sure, I am happy to help you. Can you please provide your price limit?

USER: Price limit is 500.

ASSISTANT: Ok, please provide your journey dates.

USER: I will start on 09/06 and return on 09/08.

ASSISTANT: Ok, please provide your source and destination airport codes.

USER: I will depart from DC - DCA to NV - LAS.

ASSISTANT: Ok, please wait for a moment.

USER: Ok.

ASSISTANT: Thank you for waiting. May I know your name?

USER: I am Susan King.

ASSISTANT: Ok, we are sorry to say that there is no flight found with your given details.

USER: Ok, no issues. Thanks for your response.

ASSISTANT: Thank you for reaching us.