How to print absolute path of some file from c: root in perl?

Having this perl:

#!/usr/bin/perl -w
use Cwd qw[abs_path];
use autodie;
opendir C, "c:\";
@ar = map { abs_path($_) } readdir(C) or die $!;
print $ar[0];

I am trying to print an absolute path of first file from c:, but an error:

Use of uninitialized value $ar[0] in print at C:UsersppastOneDrivePlochab.pl line 5.  

Does anyone know, what is wrong?

my @ar = map { abs_path('C:\' . $_) } readdir C;

opendir C, "C:\" or die $!;