You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, what can I do for you today?

USER: I am planning to meet my colleague in Atlanta, so please book a flight ticket from DTW to ATL.

ASSISTANT: Sure, may I know your travel dates?

USER: I want to fly on Oct 16, return on Oct 18.

ASSISTANT: Do you have any class preference?

USER: No.

ASSISTANT: Any other requirement to be met?

USER: I need a single connecting flight.

ASSISTANT: Ok, can you mention your name to proceed further?

USER: My name is Mark Brown.

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

USER: No problem, thank you.

ASSISTANT: Thank you for contacting us.