Create predefined folder & sub-folders on Windows.

@echo off

set PWD=%cd%
set dlist=CLASS01 CLASS02 CLASS03
set slist=PHY CHE BIO GEO MATH

for %%i in ( %dlist% ) do (
   if not exist %PWD%\%%i ( mkdir %PWD%\%%i )
   for %%j in ( %slist% ) do (
       if not exist %PWD%\%%i\%%j ( mkdir %PWD%\%%i\%%j )
   )
)