sub lcscount {
  my($x, $y) = @_;
  my $n = lcs($x, $y) or return 1;
  my %seen;
  my $count = 0;
  my @x = split //, $x;
  NestedLoops(
    [   
      [ 0 .. $#x ],
      ( sub { [ $_ + 1 .. $#x ] } ) x ($n - 1), 
    ],  
    sub {
      my $ssx = join '', @x[@_];
      return if $seen{$ssx}++;
      $count += (matchss($ssx, $y) or return) * matchss($ssx, $x);
    },  
  );
  $count;
}