You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you today from my end?

USER: I am Paul Moore. I need your assistance in booking my flight ticket from BOS to IAD?

ASSISTANT: Sure, I am here to help you out. Please provide me your trip dates.

USER: My depart date is Mar 25, my return date will be Mar 27.

ASSISTANT: Sorry  Paul Moore, there is no flight in your route.

USER: That's ok, thank you.

ASSISTANT: Thank you.