You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Williams Harris.

ASSISTANT: How may I aid you?

USER: I would like to book a flight ticket to attend my brother's anniversary in Washington, can you help me for booking a flight ticket from MSP to DCA?

ASSISTANT: Sure, I will help you. Please send your travelling dates.

USER: My travelling dates are Oct 02 and Oct 04.

ASSISTANT: Do you have any preferences?

USER: I am looking for the ticket in business class.

ASSISTANT: Sorry, there is no flight available which is providing business class.

USER: That's ok, no problem.

ASSISTANT: You are welcome, have a nice day.

USER: Thank you for checking.