You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

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

ASSISTANT: Sure, I can help you. Please let me know your travel dates.

USER: Sure, my travelling dates are Dec 30 - Jan 1.

ASSISTANT: Thank you. Please provide me your class preference.

USER: I am comfortable with any class.

ASSISTANT: Ok, may I know your name?

USER: Please book my flight under the name of Carol Brown.

ASSISTANT: Thank you. Please wait for a while.

USER: Sure.

ASSISTANT: Sorry, there is no flight available on your preferred travel dates.

USER: Ok, no problem. Thank you for the information.

ASSISTANT: You are welcome and thank you for choosing us.