You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: Please help me to book a flight ticket from IAD to MSP.

ASSISTANT: May I know your travel dates?

USER: My journey dates are from Oct, 12 to Oct, 14.

ASSISTANT: Do you have any connecting preferences?

USER: I need  a single connecting flight.

ASSISTANT: Is there any other concern?

USER: I prefer an economy class to fly.

ASSISTANT: May I know your name please?

USER: Dorothy Thomas.

ASSISTANT: No flights found as per preferences at the moment. Sorry for inconvenience caused, thank you for choosing us.