C# language

Prompt the user to enter a sequence of non-negative numbers that ends whenever the user enters a negative number. Have a method find the mean value for the sequence that was entered. Display that value for the user. The mean of 1 and 2 is 1.5.

Do not add other namespaces to your program besides the System namespace. Don't use Collections or LINQ or anything else that we haven't discussed directly in class.

This program can (and should) be completed successfully without using exceptions and try/catch blocks (which, technically, we haven't discussed yet either).