You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: Can you please help me to book a flight from IAD to DTW?

ASSISTANT: Please provide your travelling dates.

USER: Sure, I want to travel on Jan 24 and need to return on Jan 26.

ASSISTANT: Do you have preference?

USER: I need a connecting flight with an economy class.

ASSISTANT: May I know your name?

USER: Eric King here.

ASSISTANT: Sorry, there is no flight with your requirement.

USER: Ok, not an issue.

ASSISTANT: Thank you.

USER: Thank you for checking.