You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am David Hill, can you help me to book a flight ticket?

ASSISTANT: Sure, can you please share your trip dates and airport codes?

USER: I am planning for a trip from DCA to JFK. My preferable dates are 06/01 and 06/03.

ASSISTANT: Please give me a moment, I will check with the availability.

USER: 500 and 1 are my price and connections limits. Did you find any flight?

ASSISTANT: Sorry David, there is no flight available on your preferable dates.

USER: Oh! that's fine. Thank you for your help.

ASSISTANT: Thank you for reaching us.