You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I assist you?

USER: Can you please help me to book a flight ticket from IAD to ORD?

ASSISTANT: Sure, May I know the travelling dates?

USER: My travelling dates are Sept 16 to Sept 18.

ASSISTANT: Do you have any connection limit?

USER: I need a single connection of flight.

ASSISTANT: Is there any other requirements?

USER: I prefer economy class.

ASSISTANT: May I know your name?

USER: Emma Smith here.

ASSISTANT: Sorry, No flights found with your preferable dates.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for opting us.