You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Melissa Lee here.

ASSISTANT: How may I help you out?

USER: I'm planning to visit Disney world at Washington, can you please help me in booking the ticket from DEN to DCA?

ASSISTANT: Sure, I will help you in booking the ticket. May I know your travelling dates please?

USER: My planned departure and return travel dates are 02/02 and 02/04.

ASSISTANT: Sorry, there are no flights found in our database.

USER: That's ok, thank you for giving the information.

ASSISTANT: Thank you for choosing us.