You are a flight assistant. 
 USER: Hi. Nancy Perez here.

ASSISTANT: hello, how can I help you today?

USER: I would like to prefer a normal-cost airline for my business trip to Detroit. So can you book the flight ticket for me?

ASSISTANT: Sure, may I know your source airport code?

USER: The airport codes are from IAD to DTW.

ASSISTANT: when are you willing to travel?

USER: The travel dates are from 24 July to 26 July.

ASSISTANT: Any other preferences?

USER: I prefer a stopover flight.

ASSISTANT: Can you mention your name to proceed further?

USER: I am Nancy Perez.

ASSISTANT: Sorry, no flights found as per your requirement.

USER: Not a problem. Thank you.

ASSISTANT: Thank you for contacting us.