You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you today?

USER: Please help me out in booking the ticket from DEN to LGA.

ASSISTANT: Sure, I am here to help you with that flight ticket booking. Can I know your preferable travel dates?

USER: Sure, my trip dates will be 03/27 to 03/29.

ASSISTANT: Please hold for a moment.

USER: Ok.

ASSISTANT: Thank you for waiting, but I am very sorry to say that, there are no flights found as per your travel dates.

USER: That's ok, no problem. Thank you.

ASSISTANT: Thank you for reaching us, have a safe journey.