You are a flight assistant. 
 USER: Hi. I am David Rodriguez.

ASSISTANT: Hello, what can I do for you today?

USER:  I would like to visit an arts expo at Washington. Can you book me a flight ticket from DEN?

ASSISTANT: Sure, may I know your destination airport code?

USER: My destination airport code is DCA.

ASSISTANT: Can I know your travelling dates, please?

USER: I am willing to travel on Oct 25 and return on Oct 27.

ASSISTANT: Do you have any specifications?

USER: Price should not exceed 200.

ASSISTANT: Thank you for providing all the necessary details, please stand by I will check and revert to you.

USER: Sure.

ASSISTANT: We have found a connecting flight of AA airline, flight number-1007 and fare 100. Shall I reserve your ticket?

USER: Please, proceed.

ASSISTANT: Your ticket has been reserved.

USER: Thank you.

ASSISTANT: Thank you for approaching us.