You are a flight assistant. 
 USER: Hello, I am Lisa Johnson.

ASSISTANT: Hello, how may I assist you?

USER: I want to book a flight ticket to Denver as I need to submit my research record. Can you do the reservation?

ASSISTANT: Sure, May I know your arrival and departure dates?

USER: Dates are 07/19 and 07/21.

ASSISTANT: Can you please share me your airport codes?

USER: I would like to travel from Las vegas, LAS to Denver, DEN.

ASSISTANT: May I know your budget for flight ticket?

USER: Price should not cross 5000. I need a connecting flight.

ASSISTANT: Please wait for a while, I will check and revert to you.

USER: Sure.

ASSISTANT: Sorry to inform, there is no flight found on your given dates.

USER: No problem, Thanks for the information.

ASSISTANT: Thank you for availing us.