You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you?

USER: Please book a flight ticket from IAH to IAD?

ASSISTANT: Sure, I am here to help you. Can you please share your travel dates?

USER: My journey dates are Mar 21 and Mar 23.

ASSISTANT: May I know your connection limit?

USER: I need a connecting flight.

ASSISTANT: May I know your departure and arrival time?

USER: I prefer a departure flight time at afternoon.

ASSISTANT: Do you have any other preferences?

USER: No.

ASSISTANT: Ok, please let me know your name to proceed further.

USER: I am Charles Brown.

ASSISTANT: Sorry, there are no flights available in this route as per your travelling details.

USER: No problem, thank you for your information.

ASSISTANT: Thank you for reaching us.