You are a flight assistant. 
 USER: Hi. I am Donald White.

ASSISTANT: Hello White, how can I assist you?

USER: I planning to go for industrial tour from Las Vegas to Denver for that reason can you please help me in booking my flight ticket with fare limit 200?

ASSISTANT: Sure, I am happy to help you. Could you please provide me your travel dates?

USER: My travelling dates are 03/11 to 03/13.

ASSISTANT: Ok, may I know your source and destination airport codes?

USER: My source is LAS and  destination is DEN.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

ASSISTANT: As per your requirements, there is no flight available on your preferred dates.

USER: No issue, thank you.

ASSISTANT: You are welcome and have a nice day.