#! /usr/bin/perl -w

use strict;
use POSIX qw(ceil);

sub elgon
{
        my $string = shift;
        my @answers;
        my %char_hash = map { $_ => 1} split //, $string;
        foreach my $key (keys %char_hash)
        {
                my @appearances;
                for (my $i = 0; $i < length($string); $i++)
                {
                        push (@appearances, $i) if substr($string, $i,+ 1)  eq $key;
                }
                foreach my $start(@appearances)
                {
                        foreach my $finish(reverse @appearances)
                        {
                                next if $start >= $finish;
                                my $half_length = ceil(($finish - $start + 1) / 2);
                                push @answers, substr($string , ($start) , ($finish - $start + 1) ) if substr($string, $start
, $half_length) eq reverse substr ($string, ($finish - $half_length + 1), $half_length);
                        }
                }
        }

        return "FAILED!" if ! scalar(@answers);

        my $longest = "";
        map { $longest = $_ if length($longest) < length($_) } @answers;
        return $longest;
}