#!/usr/bin/perl

# http://perlmonks.org/?node_id=1201500

use strict;
use warnings;
$| = 1;

my $file = '/usr/share/dict/words';

open my $fh, '<', $file or die "$! opening $file";
while(<$fh>)
  {
  chomp;
  /[^a-z]/ and next;

  "$_\n$_" =~ /^
    (?=              .* (.) .* \n (?: (?:(?!\1).)* \1 ){1} (?:(?!\1).)* $ )
    (?=              .* (.) .* \n (?: (?:(?!\2).)* \2 ){2} (?:(?!\2).)* $ )
    (?= .{3,3}  \n | .* (.) .* \n (?: (?:(?!\3).)* \3 ){3} (?:(?!\3).)* $ )
    (?= .{3,6}  \n | .* (.) .* \n (?: (?:(?!\4).)* \4 ){4} (?:(?!\4).)* $ )
    (?= .{3,10} \n | .* (.) .* \n (?: (?:(?!\5).)* \5 ){5} (?:(?!\5).)* $ )
    (?= .{3,15} \n | .* (.) .* \n (?: (?:(?!\6).)* \6 ){6} (?:(?!\6).)* $ )
    (?= .{3,21} \n | .* (.) .* \n (?: (?:(?!\7).)* \7 ){7} (?:(?!\7).)* $ )
    (?= .{3,28} \n | .* (.) .* \n (?: (?:(?!\8).)* \8 ){8} (?:(?!\8).)* $ )
    (?= .{3,35} \n )
    /x and print "$_ ";
  }
print "\n";