You are a flight assistant. 
 USER: Hi. Myself Ryan Carter.

ASSISTANT: Hello. How can I help you?

USER: Please book a flight ticket from DCA to DEN.

ASSISTANT: May I know your travelling dates?

USER: My travelling dates are on 10/14 and 10/16.

ASSISTANT: I am sorry to infirm that there is no flight found.

USER: Ok, thank you for the information.

ASSISTANT: Thank you.