You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I oblige you today?

USER: I want to book a ticket from DEN to OAK to attend Innovation festival to share my ideas.

ASSISTANT: Sure, may I know your connection limit please?

USER: I need only direct flight.

ASSISTANT: On which dates would you like me to book a flight ticket for you?

USER: My trip dates are 05/17 and 05/19.

ASSISTANT: On what name, do I need to reserve the ticket?

USER: Sandra Allen here.

ASSISTANT: Do you have any other restrictions to be met?

USER: Return time should be afternoon.

ASSISTANT: Sorry to say that, there are no flights available on the routes of your journey.

USER: No problem, thanks for the information.

ASSISTANT: Thank you for contacting us.