You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, How can I assist you?

USER: Can you help me to book a flight from EWR to DCA?

ASSISTANT: Sure, May I know the journey dates?

USER: My travelling dates are Apr 19 and 21.

ASSISTANT: Do you have any connection limit?

USER: I prefer connecting flight.

ASSISTANT: Do you have any airline preference?

USER: I am fine with any airlines.

ASSISTANT: Is there any other requirements?

USER: No.

ASSISTANT: May I know your name?

USER: My name is Justin Adams.

ASSISTANT: Please wait a second.

USER: Ok.

ASSISTANT: Sorry, No flights found with your preferable dates.

USER: No issues, thank you for your time.

ASSISTANT: Thank you for opting us.