To run:
- change into the year and day directory.
- then type:
    cat input.txt | ./day#X.pl

Minimalist output

Attempts have been made to ensure that
    perlcritic -1 day#X.pl
should only complain about the print.

The last part of the current history is not necessarily finished.

You may need to install various perl libraries.
They typically map from Foo::Bar::Baz to libfoo-bar-baz-perl, so
    sudo apt install libfoo-bar-baz-perl
should install the missing library.

Minimalist README, because programmers don't write documentation!