You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I be your helping hand today?

USER: I have a conference at Cobo Center in Chicago. Can you book me a ticket with a direct flight?

ASSISTANT: Sure, Is there any class preferences?

USER: No , I am comfortable with any class.

ASSISTANT: Ok, when do you want to depart and return?

USER: Sure, I will depart on 08/25 and return on 08/27.

ASSISTANT: Ok, please provide your source and destination airport codes.

USER: Sure, I am heading from Orlando, FL - MCO. Destination airport code is IL - ORD.

ASSISTANT: Ok, May I know your good name?

USER: Sure, you can reserve my ticket on the name of Andrew Edwards.

ASSISTANT: Thank you for providing details, please wait.

USER: Sure.

ASSISTANT: Thank you for your patience, we did not find any flights with your given specifications.

USER: Ok, I will choose another alternative to go. Thank you.

ASSISTANT: Thank you for opting us.