You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how can I help you?

USER: I am Patrick Miller. I need to book a flight ticket to Washington with my friends to attend for a meeting from Las Vegas. Can you help me for booking?

ASSISTANT: Sure, may I know your source and destination airport codes?

USER: My source is NV-LAS and destination is DC-DCA.

ASSISTANT: Let me know your price limit.

USER: Price limit is below 1000.

ASSISTANT: Could you please provide me your planned journey dates?

USER: My planned journey dates are 09/04 and 09/06.

ASSISTANT: Ok, please wait for a moment.

USER: Sure.

ASSISTANT: Sorry, no flights found with your given dates.

USER: Thank you for your information.

ASSISTANT: Thanks for choosing us.