while( @$items > 10) {

  my( $item1, $item2 );
  my( $item1_idx, $item2_idx );
  my $difference = 9999; #Arbitrary large number
  for my $i ( 0 .. $#$items ) {
    my $d1 = $items->[$i];

    for my $j ( 0 .. $#$items ) {
      my $d2 = $items->[$j];

      next if $i == $j;

      my $diff = max_diff( $d1, $d2 );
      if( $diff < $difference ) {
        $difference = $diff;
        ($item1,$item2) = ($d1,$d2);
        ($item1_idx,$item2_idx) = ($i,$j);
      }

      last if $difference == 0;
    }

    last if $difference == 0;
  }

  splice( @$items, $item1_idx, 1 );
  splice( @$items, $item2_idx, 1 );
  my $c = merge( $item1, $item2 );

  push @$items, $c;
  print "         \r";
  print scalar @$items, "\r";
}

sub merge {
  my( $x, $y ) = @_;

  # Both non-clusters
  if( ref $x eq 'HASH' and ref $y eq 'HASH' ) {
    return [$x,$y];
  }
  # $x cluster
  elsif( ref $x eq 'ARRAY' and ref $y eq 'HASH' ) {
    return [$x,$y];
  }
  # $y cluster
  elsif( ref $x eq 'HASH' and ref $y eq 'ARRAY' ) {
    return [$y,$x];
  }
  elsif( ref $x eq 'ARRAY' and ref $y eq 'ARRAY' ) {
    return [$x,$y];
  }
  else {
    die "Wtf? $x $y";
  }
}

sub max_diff {
  my( $d1, $d2 ) = @_;

  #my %x1 = map { $_->name, undef } $d1->words;
  #my %x2 = map { $_->name, undef } $d2->words;

  if( ref $d1 eq 'HASH' and ref $d2 eq 'HASH' ) {
    my %x1 = %{$d1->{words}};
    my %x2 = %{$d2->{words}};

    my %y1 = %x1;
    my %y2 = %x2;

    delete @x1{keys %x2};
    delete @y2{keys %y1};

    return( ( scalar keys %x1 )  + ( scalar keys %y2 ) );
  }
  elsif( ref $d1 eq 'ARRAY' and ref $d2 eq 'HASH' ) {
    my $x = max_diff( $d1->[0], $d2 );
    my $y = max_diff( $d1->[1], $d2 );

    return $x > $y ? $x : $y;
  }
  elsif( ref $d1 eq 'HASH' and ref $d2 eq 'ARRAY' ) {
    my $x = max_diff( $d2->[0], $d1 );
    my $y = max_diff( $d2->[1], $d1 );

    return $x > $y ? $x : $y;
  }
  elsif( ref $d1 eq 'ARRAY' and ref $d2 eq 'ARRAY' ) {
    my $x = max_diff( $d1->[0], $d2->[0] );
    my $y = max_diff( $d1->[1], $d2->[1] );
    my $xx = max_diff( $d1->[0], $d2->[1] );
    my $yy = max_diff( $d1->[1], $d2->[0] );

    return max( $x, $y, $xx, $yy );
  }
  else {
    die "Wtffffff $d1 $d2";
  }
}