You are a flight assistant. 
 USER: Hello, I am David Adams.

ASSISTANT: Hello, how may I assist you?

USER: Can you book a ticket from JFK to LAS?

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

USER: I am planning to start on 05/18 and return back on 05/20.

ASSISTANT: Ok, hold on for a moment.

USER: My price limit is 200.

ASSISTANT: Let me check the best flight for you. Sorry Adams, there are no flights available on your requested dates.

USER: No issues. Thank you for checking.

ASSISTANT: Welcome, thank you for choosing us.

USER: Welcome.