And if you had warnings enabled you would have got warnings about unrecognized escapes. Putting them in I got these messages:

Unrecognized escape \H passed through at Perl-1.pl line 22.
Unrecognized escape \P passed through at Perl-1.pl line 22.
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It is considered good practice to start each script with

use warnings;
use strict;
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which will pick up a lot of these types of problems.