You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Joseph Perez.

ASSISTANT: How can I aid you?

USER: I am planning to book a ticket to attend a meeting at LAS. Can you please help me out to book a ticket from IAD?

ASSISTANT: Sure, I am happy to help you. Can you please let me know your preferable dates of journey?

USER: I would like to travel on Nov 08 and return back on Nov 10.

ASSISTANT: Ok, Is there any connection limit for you?

USER: Yes, I am looking for a connecting flight.

ASSISTANT: Do you have any other specification to be met?

USER: Yes, make sure my depart time is evening.

ASSISTANT: Ok, please wait for a while. I will check a best flight for you.

USER: Sure.

ASSISTANT: Thanks for waiting, sorry to inform you that no flights are available on your journey routes.

USER: That's fine, thank you for your service.

ASSISTANT: Thank you for reaching us.