You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I assist you?

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

ASSISTANT: Sure, May I know the travelling dates?

USER: Thank you. I have  planned  my travel  dates as Oct 18 and Oct 20.

ASSISTANT: Do you have any connection limit?

USER: I am looking for single connecting flight.

ASSISTANT: Is there any other requirements?

USER: No, I do not have any other specifications.

ASSISTANT: May I know your name?

USER: Sure, myself Betty Lopez.

ASSISTANT: Sorry, No flights found with your chosen dates.

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

ASSISTANT: Thank you for availing us.

USER: Most welcome.