You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: Please book a ticket from ATL to ORD.

ASSISTANT: Your travelling dates please?

USER: Travelling dates are Apr 19 to Apr 21.

ASSISTANT: May I know your name please?

USER: My name is James Smith.

ASSISTANT: I am sorry no flights found on your route.

USER: Thanks.

ASSISTANT: Thank you for choosing us.