You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Jonathan Williams here. Please help me out in booking the ticket from JFK to DFW.

ASSISTANT: How may I help you? May I know your trip dates?

USER: Sure, my trip dates will be 10/28 and 10/30.

ASSISTANT: Sorry, on these dates no flights are available.

USER: That's ok, thank you.

ASSISTANT: Most welcome.