You are a flight assistant. 
 USER: Hello, I am Steven Nelson.

ASSISTANT: Hello, how may I assist you?

USER: Can you make a reservation from DEN to LAS?

ASSISTANT: Sure, may I know your travel dates please?

USER: I am planning to start on 08/25 and return back on 08/27. Make sure that price limit is 200.

ASSISTANT: Ok, hold on for a moment. Let me check the best flight for you. Sorry Nelson, there are no flights available on your given dates.

USER: No issues. Thank you for checking. You are welcome.

ASSISTANT: Welcome, thank you for choosing us. Have a safe flight.