You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: This is Michael Williams, can you help me to book a flight ticket from IAD to MCO?

ASSISTANT: Sure, I am here to help you. May I know your travel dates?

USER: My preferable journey dates are May 18 and May 20.

ASSISTANT: Ok, do you have any requirements?

USER: I would like to depart in the evening.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

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

USER: No problem, thank you for the information.

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