You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you for the day?

USER: I am planning to visit Denver, can you please book me a ticket from DTW to DEN?

ASSISTANT: Sure, may I know your dates of travel?

USER: I would like to depart at July 28 and would like to return at July 30.

ASSISTANT: Do you have any specifications?

USER: I prefer afternoon return flight for this journey.

ASSISTANT: May I know your name?

USER: My name is Andrew Lopez.

ASSISTANT: Ok, please wait a minute.

USER: Sure.

ASSISTANT: Sorry, there were no flights found on your route.

USER: Ok, not an issue. Thank you for providing information.

ASSISTANT: Thank you for opting us.