You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you for the day?

USER: I am planning to visit Washington, will you help me in booking the flight ticket from LAS to DCA?

ASSISTANT: Sure, I am here to help you with that. Can you please share your preferable travel dates?

USER: My travelling dates are July 20 and July 22.

ASSISTANT: May I know your name please?

USER: Myself Michael Gonzalez.

ASSISTANT: Is there any airline preference?

USER: I always prefer Normal-cost airlines.

ASSISTANT: Do you have any other specifications?

USER: No, thank you for asking.

ASSISTANT: Sorry to say that, there are no flights found on this route as per your travel dates.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for reaching us, have a great day.