....besides the fact that most of your variables are not defined?

use strict;
use warnings;
use 5.010;


my $th = 'hello-10-world-20';
my %things = split /-/, $th;

while ( my($key, $val) = each %things ) {
    say "$key => $val";
}

--output:--
hello => 10
world => 20
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What do you consider to be the 'first' key/value pair in a hash?