You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you?

USER: Mary Brown here. I would like to prefer a economy class flight for my business trip to Washington. Can you book the flight ticket for me?

ASSISTANT: Sure, may I know your planned travel dates please?

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

ASSISTANT: Can you please share your airport codes?

USER: The airport codes are from PHL to DCA.

ASSISTANT: Would you like to travel in a connecting flight or a direct flight?

USER: I am looking for a stopover flight.

ASSISTANT: Do you have any other specifications?

USER: No, that is it.

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

USER: Not a problem.

ASSISTANT: Thank you for reaching us.

USER: Thank you.