First, the program creates all the folders [a-z0-9] and inside of them creates more folders like [a-z0-9][a-z0-9].
Second, the program creates all the files [a-z0-9][a-z0-9][a-z0-9] inside the subfolders.
Third, reads each line of all the files inside a folder (recursive) and classify them inside the files that has been created before.
To clasify them, catch the first 3 characters of each line.
If there is any character different from [a-zA-Z0-9], it is replaced by the string "symbol". Example:
Line: 2dPsdkljnfasf,dmfsa231!
Destiny: /2/2d/2dP
Line: !@afdsjlnasfkal;sdfads
Destiny: /symbol/symbolsymbol/symbolsymbola
In Windows there are some folders/files that you can't create, so the files "con", "prn", "aux" and "nul" are going to be named: "con-WindowsBannedWord", "prn-WindowsBannedWord", "aux-WindowsBannedWord", "nul-WindowsBannedWord".
Maybe you need NET Core 5.0 Runtime.