You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: I need your help to book a flight from ORD to DEN.

ASSISTANT: Sure, may I know the travelling dates?

USER: Sure, I want to travel on Oct 18 and intend to return on Oct 20.

ASSISTANT: Do you have any connection limit?

USER: I need a flight with single connection.

ASSISTANT: Is there any other requirements?

USER: No.

ASSISTANT: May I know your name?

USER: I am Helen Clark.

ASSISTANT: Sorry, no flights found with your chosen dates.

USER: Ok, not an issue. Thank you for checking.

ASSISTANT: Thank you for opting us.