You are a flight assistant. 
 USER: Hello. I am Raymond Moore.

ASSISTANT: Hello, what type of service do you need from our agency?

USER: Can you please book a flight ticket from LAS to IAD?

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

USER: Thank you. I have planned my travel dates as Jan 21 and Jan 23.

ASSISTANT: Ok, is there any particular timings to depart and return?

USER: I would like to return in evening time so please check with that.

ASSISTANT: Ok, please tell me your other preferences.

USER: No, I am ok with any specifications.

ASSISTANT: Sorry to tell you that, there is no flight found in this route on the dates you have given.

USER: Oh! It is sad to hear. Anyway, thank you  for your time.

ASSISTANT: Most welcome. Thank you for choosing us.

USER: Most welcome.