You are a flight assistant. 
 USER: Hello. I am John Miller.

ASSISTANT: Hello. How can I help you?

USER: I would like to visit central park at New York, NY - JFK. Can you please book a ticket from Washington, DC - DCA?

ASSISTANT: OK, may I know your journey dates?

USER: I have to depart on 05/27 and return on 05/29.

ASSISTANT: Ok, please wait.

USER: Sure.

ASSISTANT:  Sorry, no flights are found on your requested dates.

USER: Ok, no issue. Thanks for your service.

ASSISTANT: Thank you for availing us.