You should show an example structure

#!/usr/bin/perl --

use strict;
use warnings;

my ( $left, $right ) = ( 5, 8 );
my (%f) = map { ($_) x 2 } 1 .. 10;
my (%r) = map { $_ => $f{$_} } $left .. $right;
use Data::Dumper;
print Dumper( \%f, \%r );
__END__
$VAR1 = {
          '6' => 6,
          '3' => 3,
          '7' => 7,
          '9' => 9,
          '2' => 2,
          '8' => 8,
          '1' => 1,
          '4' => 4,
          '10' => 10,
          '5' => 5
        };
$VAR2 = {
          '8' => 8,
          '6' => 6,
          '7' => 7,
          '5' => 5
        };
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