#!/usr/bin/perl
use strict;
use warnings;
use feature qw/say/;
use 5.10.1;

my @rand=();

my $all_the_numbers=int(rand(19));

my $i=0;

while ($all_the_numbers<20)
{
 my $number=20-int(rand(30));
 push @rand, $number;
 $i++;
 last if $i==$all_the_numbers;
}
say "@rand";

my $h=0;

while ($all_the_numbers<20)
{
 for (@rand)
 {
 if ($rand[0]<0)
  {
   next;  #in order to make it skip the negative ones
  }
   shift @rand;
 }
 $h++;
 last if $h==$all_the_numbers;
}
say "@rand";