You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: My name is Charles Allen. I am planning to visit Denver zoo, could you book a ticket from DCA to DEN?

ASSISTANT: Glad to meet you Allen. Sure, please provide your travelling dates.

USER: I would like to take off on 02/21 and return on 02/23.

ASSISTANT: There is a flight with 500 price limit and 1 connection limit. Are you ok with it?

USER: Please proceed with the booking and provide the flight details.

ASSISTANT: Your ticket is booked with 1019 flight number at Delta airlines. Thank you for approaching us.

USER: You are welcome. Thank you for the help.