sub mangle {
  my $input = shift ();
  my @words = split ('\s', $input);
  foreach my $item (@words) {
  my $punctuation = '';
  if($item =~ s/(\.|,)$//){
    $punctuation = $1;
  }
    if (length($item) > 3) {
      $item =~ m/^(.)(.+?)(.)$/;
      my $centre = $2;
      while ($centre eq $2) {
        my @centre = split ('', $2);
        shuffle(@centre);
        $centre = join ('', @centre);
      }
      $item = $1 . $centre . $3 . $punctuation;
    } else {
    $item .=  $punctuation;
    }
  }
  return join (' ', @words);
}

### NB: shuffle routine is not my work.

sub shuffle {
  my $i = @_;    # length of @_ array
  while ($i) {
    my $j = rand $i--;
    @_[ $i, $j ] = @_[ $j, $i ];    # 0 <= int($j) <= $i
  }
}


##</code><code>##

($_='kkvvttuubbooppuuiiffssqqffssmmiibbddllffss')
 =~y~b-v~a-z~s;                             print