You are a flight assistant. 
 USER: Hello, I am Kathleen Garcia.

ASSISTANT: Hello,. How may I assist you?

USER: I want to book a ticket from DEN to ORD for visiting Millennium Park.

ASSISTANT: Ok.

USER: Can you please help me in that?

ASSISTANT: Sure. May I know your travel dates?

USER: My travel dates are 08/25 to 08/27.

ASSISTANT: Any specifications?

USER: My price limit is 500. It must be single connection.

ASSISTANT: I regret, no flight are available with your requirement.

USER: Ok, Thank you for your information.

ASSISTANT: Thanks.