You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Angela Jackson here.

ASSISTANT: How can I assist you today?

USER: I would like to prefer a flight with lay-by option for my business trip to Washington. Can you book it?

ASSISTANT: Sure, can you please share your travel dates?

USER: The travel dates are from 25 Mar to 27 Mar.

ASSISTANT: Could you please help me with the airport codes?

USER: The airport codes are from DEN to IAD.

ASSISTANT: May I know your connection limit?

USER: I prefer a stopover flight.

ASSISTANT: Do you have any other specification that you are looking for?

USER: No.

ASSISTANT: I am sorry to inform you that there is no flight available at your request.

USER: Not a problem. Thank you.

ASSISTANT: Thank you for contacting us.