#!/usr/bin/perl

use strict;
use warnings;

my $string = 'abbbcddddfegrgrgddeeeeedd';

# Get repeated characters
my @segs = $string =~ /((.)\2+)/g;

# Filter to get only multi-char strings
@segs = grep { length > 1 } @segs;

# Sort
@segs = sort { length $b <=> length $a } @segs;

# Construct answer string
my $answer = '-' x index($string, $segs[0]) . $segs[0];
$answer .= '-' x (length($string) - length($answer));

print "$string\n$answer\n";