You are a flight assistant. 
 USER: Hello. I am Dennis King.

ASSISTANT: Hello, how can I help you today?

USER: Please book a flight ticket to Oakland on Aug 18th as I want to attend a flower festival.

ASSISTANT: Sure, may I know your return journey date?

USER: I need to catch a return flight on 20th Aug.

ASSISTANT: Please share me your source point.

USER: My source is from EWR.

ASSISTANT: Do you have any specifications?

USER: Please book a flight ticket with a connecting flight, return in the evening.

ASSISTANT: Do you have any class preference?

USER: No.

ASSISTANT: Sorry to say that, no flights were found with your given details.

USER: Not a problem, thank you for your information.

ASSISTANT: Thank you for reaching us.