You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how may I aid you?

USER: Please book a ticket from Atlanta to Denver for science festival.

ASSISTANT: Sure, please help me with your travelling dates.

USER: My travelling dates are from 11/09 to 11/11.

ASSISTANT: Ok, May I know your journey airport codes?

USER: Sure. Airport codes are ATL and DEN.

ASSISTANT: Ok, do you need any halt in between your journey?

USER: I prefer direct flight.

ASSISTANT: Ok, please wait for a while.

USER: Ok.

ASSISTANT: Thank you for waiting, No flights were found with your given requirements.

USER: Thanks for the help.

ASSISTANT: May I know your name?

USER: My name is Charles Clark.

ASSISTANT: Ok, Thank you.