You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you?

USER: I am Justin White. I want to book a plane from Washington, DC - IAD to Washington, DC - DCA. My depart and arrival dates will be on Mar 29 and Mar 31.

ASSISTANT: Thanks for giving information, please wait for a while, let me check and get back to you.

USER: I need a direct flight with a price limit of 500.

ASSISTANT: OK. We are very sorry to inform you that there is no flight available on this date.

USER: OK, no issue. Thanks for your response.

ASSISTANT: Thanks for your valuable time. Have a good day.