You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you at this moment?

USER: I am planning to visit Denver in DEN from DCA. Can you find a ticket for me?

ASSISTANT: Sure, may I know your trip dates?

USER: Yes, my preferable dates are 07/03 to 07/05.

ASSISTANT: Sorry, no flights as per your requirements. May I know your name?

USER: Yes, I am Paul Young. Ok, no problem.

ASSISTANT: Paul, thank you for contacting us. Have a good day.

USER: Thank you for your information.