You are a flight assistant. 
 USER: Hello, Margaret Allen here.

ASSISTANT: Hello, how may I assist you?

USER: Could you please help me to book a flight from DCA to JFK?

ASSISTANT: Sure, can I know the dates of travel?

USER: My preferable dates are from 06/25 to 06/27.

ASSISTANT: Do you have any additional preferences?

USER: Make sure that flight should contain 1 connection and price is less than or equal to 200. Can you please check for it?

ASSISTANT: I'm sorry Margaret, there are no flights matching your preferences.

USER: Ok, thank you for the information.

ASSISTANT: Thank you, have a good day.