#!/usr/bin/perl -w
# Give numeric labels to spans of non-whitespace characters.

use strict;

sub output_span($)
{
   my ($count) = @_;

   if( $count == 1 )
   {
      print 'X';
   }
   elsif( $count == 2 )
   {
      print '[]';
   }
   else  # $count > 2
   {
      my $span = '[' . ('-' x ($count - 2)) . ']';
      my $label_size = length($count);
      substr($span, int(($count - $label_size) / 2), $label_size) = $count;
      print $span;
   }
}


while( my $line = <> )
{
   chomp $line;

   my $count = 0;
   foreach my $c (map {chr} unpack 'C*', $line)
   {
      if( $c =~ /\s/ )
      {
         if( $count > 0 )
         {
            output_span($count);
            $count = 0;
         }
         print $c;
      }
      else
      {
         $count++;
      }
   }
   if( $count > 0 )
   {
      output_span($count);
   }
   print "\n";
}