You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Brian Baker.

ASSISTANT: How may I help you?

USER: I would like to book a flight ticket on dates from 10/03 to 10/05.

ASSISTANT: Ok Brian, please provide the airport codes?

USER: The airport codes are DCA and LAS respectively.

ASSISTANT: Ok, please hold on for a moment.

USER: Sure.

ASSISTANT: Sorry, there are no flights found on your requested dates.

USER: That's fine. Thank you for your time.

ASSISTANT: Thank you, have a nice day.