#!/usr/bin/perl

# http://perlmonks.org/?node_id=1169432

use strict;
use warnings;

my ($answer, $letters);

while(<DATA>)
  {
  my ( $let, $start, $end) = /(?:(\w) )?(\d+)-(\d+)/;
  if( $let )
    {
    $letters |= "\0" x $start . $let x ($end - $start + 1);
    }
  else
    {
    $_ = $letters & "\0" x $start . "\xff" x ($end - $start + 1);
    $answer .= "$1 $-[0]-" . ($+[0] - 1) . "\n" while /(\w)\1*/g;
    }
  }
1 while $answer =~ s/^(\w).*\K\n\1 /,/gm;
print $answer;

__END__
a 11-23
b 33-39
c 40-45
d 48-58
1-34
35-39
40-42
43-49
51-59
62-90