You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, do you need any help from us?

USER: I planned to meet my cousin in SFO, can you please help me to book a flight ticket from IAD?

ASSISTANT: Sure, may i know your trip dates?

USER: I prefer to travel on Jan 7 and Jan 9.

ASSISTANT: Ok, could I have your name please?

USER: I am Frank Brown.

ASSISTANT: Ok, do you need direct or connecting flight?

USER: I prefer to travel in a connecting flight.

ASSISTANT: Ok, may I know your airline preference?

USER: I would like to travel in a business class.

ASSISTANT: Sorry, there is no flight with your request.

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

ASSISTANT: You are welcome.