You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you?

USER: I am Dennis Roberts. Can you please help me in booking my flight ticket in direct flight?

ASSISTANT: Sure, may I know travelling dates please?

USER: My travelling dates are 10/17 and 10/19.

ASSISTANT: Your airport codes please?

USER: My trip codes are DEN to BOS.

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

USER: Ok, fine thank you for checking.

ASSISTANT: Thank you.