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

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

my @rand=();
for (1..$all_the_numbers) {
	push @rand, 20-int(rand(30));
}
say "@rand";

for (1..$all_the_numbers) {
	for (@rand) {
		if ( $rand[0]<0 ) { next; }  # skip the negative ones
		shift @rand;
	}
}
say "@rand";

##</code><code>##

for (@rand) {
	if ( $rand[0]<0 ) { next; }
	shift @rand;
}

##</code><code>##

for (@rand) {
	if ( $rand[0]<0 ) { next; }
	else { shift @rand; }
}

##</code><code>##

for (@rand) {
	if ( $rand[0]>=0 ) { shift @rand; }
	else { next; }
}