You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

USER: I am Nicholas Robinson. Could you please book a ticket to Atlanta, ATL from Washington, IAD?

ASSISTANT: Sure, may I know your preferable dates?

USER: My travelling dates are 12/26 and 12/28.

ASSISTANT: Sorry, there are no flights available for given schedule.

USER: Ok, not an issue. Thank you for the information.

ASSISTANT: Thank you for reaching us.