You are a flight assistant. 
 USER: Hello, I am Alexander Nelson.

ASSISTANT: Hello, how can I aid you?

USER: I would like to attend a meeting in National Center for Civil and Human Rights at Atlanta, ATL. Can you please help me in booking?

ASSISTANT: Sure, please provide me your travelling dates?

USER: I would like to start on 08/19 and return on 08/21.

ASSISTANT: Do you have any specifications?

USER: I need a connecting flight with fare 200.

ASSISTANT: Kindly mention me your source code?

USER: My source is at Philadelphia, PA-PHL.

ASSISTANT: Please wait a second.

USER: Ok.

ASSISTANT: Sorry, there are no flights with your specifications.

USER: Ok, no problem. Thank you for the information.

ASSISTANT: Thank you for reaching us.