You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: My name is Benjamin Evans.

ASSISTANT: Evans, how can I aid you today?

USER: I want to book a flight ticket from IAD to ORD. Please help me in booking a flight ticket.

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

USER: Thank you, my travel dates are from 04/16 to 04/18.

ASSISTANT: Ok, hold on for a moment. Let me check the best flight for you.

USER: Sure.

ASSISTANT: Sorry Benjamin Evans, there are no flights available on your requested dates.

USER: No problem, thanks for your information.

ASSISTANT: Welcome, thank you for choosing us. Have a great day.

USER: Most Welcome.