You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Dennis Anderson here.

ASSISTANT: How can I help you at this moment?

USER: Can you book a flight ticket for my airport codes that is from LAS to IAD?

ASSISTANT: Sure, I will help you with that. Can you please mention your preferable travel dates?

USER: The travel dates are from 22 Jan to 24 Jan.

ASSISTANT: Do you have any preferences regarding timings of your journey?

USER: The return time would be evening.

ASSISTANT: Are you ok with connecting flight or you need a direct flight?

USER: I need  a single connecting flight.

ASSISTANT: Ok, please hold on a moment.

USER: Sure.

ASSISTANT: Sorry, no flights are available in this route as per your requested dates.

USER: Not a problem.

ASSISTANT: Thank you for reaching us.

USER: Thank you.