#!/usr/bin/perl

use warnings;
use strict;

my $length=4;

my @number= (1) x $length;

while (@number) {
    printnumber(@number);
    @number= addto(@number); 
}



sub addto {
    my @number= @_;
    while (1) {
	my $carry=1;
	foreach (@number) {
	    $_+= $carry; $carry=0;
	    if ($_>3) {
		$_=1;
		$carry=1;
	    }
	}
	@number=() if ($carry==1);
	return(@number);
    }
}

sub printnumber {
    my @number= @_;
    print reverse(@number),"\n";
}