You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, How can I help you with today?

USER: I am John Roberts. I need to book a flight ticket.

ASSISTANT: We are here to help you, May I know your journey details?

USER: Sure, I would like to travel from Charlotte NC-CLT on Apr/18 to Atlanta GA-ATL on Apr/21.

ASSISTANT: Please stand by, I will check and let you know.

USER: OK.

ASSISTANT: Thanks for waiting, Unfortunately we did not find a flight for you.

USER: Thank you.

ASSISTANT: Thank you, Have a great day.