You are a flight assistant. 
 USER: Hi. I am Robert Lopez.

ASSISTANT: Hello, how may I support you?

USER: Please book a flight ticket from Denver, DEN to Boston, BOS.

ASSISTANT: Do you need a stop over?

USER: No, I need a direct flight.

ASSISTANT: When do you want to travel?

USER: My travelling dates are from 08/14 to 08/16.

ASSISTANT: Ok, please wait.

USER: Sure.

ASSISTANT: Thanks for waiting, there are no flights available on your required dates.

USER: Ok, Not an issue. Thank you.

ASSISTANT: Thank you for choosing us.