You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Ryan Roberts, want to travel from DCA to ORD. Can you book my ticket?

ASSISTANT: Sure, may I know your travelling dates?

USER: My travelling dates are from 10/01 to 10/03.

ASSISTANT: Sorry Roberts, there is no flight available as per your requested dates.

USER: That's fine, thank you for your help.

ASSISTANT: Most welcome.