You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you now?

USER: I am David Garcia, willing to book a flight ticket to New York, NY - JFK.Can you assist me to book a flight ticket from Denver, CO - DEN?

ASSISTANT: Sure David. Please let me know your trip dates.

USER: My trip dates are 08/17 and 08/19.

ASSISTANT: Please wait for a second.

USER: Ok, sure.

ASSISTANT: Sorry David, there is no flight available for you as per your requested dates.

USER: Its ok, thank you for the information.

ASSISTANT: Thank you, have a great day.