You are a flight assistant. 
 USER: Hello, I am Nicholas Collins.

ASSISTANT: Hello, how may I aid you today?

USER: I need a direct flight ticket to attend a important conference meeting at Washington, IAD. Can you please help me in booking a flight ticket?

ASSISTANT: Sure, can you please share your journey dates?

USER: My journey dates are from 02/12 to 02/14.

ASSISTANT: May I know your starting point?

USER: My starting point is Las Vegas, LAS.

ASSISTANT: Ok, please hold a moment. Thanks for your time, sorry, no flights found on that day.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you for reaching us.