use strict;
use warnings;
my $str="";
for $str('aaa'..'ccc')
{
	
	if($str=~m/^[abc]{3}$/)
	{
		if($str!~m/(.*a.*a)/)
		{
			if($str!~m/(.*b.*b)/)
			{
				if($str!~m/(.*c.*c)/)
				{
					print "\' $str \' is a Match\n";
				}
				else
				{
					print "The string $str contains duplicated 'c'\n";
				}
			}
			else
			{
				print "The string $str contains duplicated 'b'\n";
			}
		}
		else
		{
			print "The string $str contains duplicated 'a'\n";
		}
	}
	else
	{
		print "Either the string \'$str\' contains a character not belonging to the class [abc] or is more than 3 characters\n";
	}
}

##</code><code>##

use strict;
use warnings;
my $str="";
for $str('aaa'..'ccc')
{
	if($str=~m/^[abc]{3}$/ && $str!~m/(.*a.*a)/ && $str !~ m/(.*b.*b)/ && $str!~ m/(.*c.*c)/)
	{
		print "\' $str \' is a Match\n";
	}
	
}