#!/usr/bin/perl -w
use strict;

my @chars=(('a'..'z'),(0..9));
tld('',$_) for (3..6);

sub tld{
  my ($txt,$cnt)=@_;
  if($cnt==0){
    print "$txt\n";  
  }else{
    tld($txt.$_,$cnt-1) for (@chars);
  }
}