Con is a reserved word in Windows

[pdarragh]

Per MSDN (emphasis mine, extra text omitted):

Do not use the following reserved names for the name of a file:

CON, [...]. Also avoid these names followed immediately by an extension[...].

I suggest renaming the con language to something like connive. A bit longer, but still alphabetically appropriate and will not cause issues for students trying to interact with the languages on Windows.