use warnings;
	use strict;
	$\ = $/;
	my $A = 2;
	
	my $_0to2 = join '', 0 .. 2;
	$_ = join '=', ( $_0to2 ) x 2;
	
	print "\$_:[$_]";
	
	print /^
		\d*(\d)\d* = \d*(\d)\d*
			(?(?{ my %h; map $h{ $_ } ++, $1, $2; 2 == keys %h }) | (*FAIL) )
			(?(?{ $1 < $2 }) | (*FAIL) )
			(?(?{ my $sum = $1 + $2; $sum == $A }) | (*FAIL) )
		$/x ?
			"MATCHED: \$1:[$1], \$2:[$2]"
		:
			"NOT_MATCHED"
		;

##</code><code>##

$_:[012=012]
NOT_MATCHED
##</code><code>##

$_:[012=012]
MATCHED: $1:[0], $2:[2]
##</code><code>##

(?(?{ my %h; map $h{ $_ } ++, $1, $2; print 0 + keys %h; 2 == keys %h }) | (*FAIL) )