You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Jonathan Collins.

ASSISTANT: Collins, how can I assist you today?

USER: I am planning to visit New York, JFK. Can you please book me a ticket from Denver, DEN?

ASSISTANT: Sure, I will help you. Please provide me your trip dates.

USER: My preferable journey dates are from 04/28 to 04/30.

ASSISTANT: Ok, please wait for a moment.

USER: Sure, please search for direct flight on this route.

ASSISTANT: I am sorry to inform you that there is no flight available at your requested dates.

USER: Ok, not an issue. I will find any alternate for this trip. Thank you for providing information.

ASSISTANT: You are welcome, have a nice day.