You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: I'm Christopher Martin. I am planing to visit National Zoological Park in IAD.

ASSISTANT: Good to hear that.

USER: Can you book a ticket from my current location JFK?

ASSISTANT: Sure, I can help you with that. Can I know your probable travelling dates?

USER: I had leaves in the middle of the month. So, I am planning it from 05/14 to 05/16.

ASSISTANT: Ok, let me check for the availability of flight.

USER: Ok.

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

USER: It's fine. Anyway, thank you for your help.

ASSISTANT: You are welcome. Thank you for contacting us.