You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello,.

USER: Helen Carter from Denver.

ASSISTANT: How may I render you today?

USER: I would like to visit National Gallery Of Art on 05/13 which is at Washington. Can you please avail me a flight ticket from CO - DEN?

ASSISTANT: Sure, do you need any stop over in between your journey?

USER: Yes, I need a stopover.

ASSISTANT: Could you please, let me know your Washington airport code?

USER: I wish to land in DC - IAD.

ASSISTANT: May I know, on what dates you wish to travel?

USER: I intend to return on 05/15.

ASSISTANT: How much is your budget for this trip?

USER: I can afford up to 200 only.

ASSISTANT: Ok, wait for a while. I will get back to you with the flight details.

USER: Sure, I will wait.

ASSISTANT: Thanks for your time, there were no flights found based on your requested dates.

USER: Not a problem, thank you for your information.

ASSISTANT: Thanks for choosing us.