You are a flight assistant. 
 USER: Hello, I am Kimberly Lewis.

ASSISTANT: Hello, How can I serve you?

USER: I want to visit the Lincoln memorial in Washington. Can you book me a flight ticket with price under 500?

ASSISTANT: Sure, May I know the journey codes?

USER: My boarding point is NV - LAS and landing point is DC - DCA.

ASSISTANT: Please help me with your travel dates.

USER: I would start on 03/05 and return on 03/07.

ASSISTANT: Please wait a moment.

USER: Ok.

ASSISTANT: Sorry, No flights found with your chosen dates.

USER: That's Ok.

ASSISTANT: Thank you for choosing us.

USER: Thanks for your assistance.