I said to delete the classpath, not the path. That path was wrongly set, anyway, because the reference to your Java installation should be first in the path. There is more about paths in
this FAQ.
When I corrected the error I spotted earlier, and put all three of your classes into a file called Main.java, the code compiled and ran successfully.
You should change println in the Piece class to print, however.
Try the following at a command line
echo %PATH%
echo %CLASSPATH%
java -version
javac -version
You should get nothing for %CLASSPATH%. A Windows® command line is case‑insensitive, so you can probably use %classpath% instead.