sub lcs {
  my($x, $y) = @_;
  my(@v, $cx, $cy, $left, $above);
  for my $xi (0 .. length($x) - 1) {
    $cx = substr $x, $xi, 1;
    for my $yi (0 .. length($y) - 1) {
      $cy = substr $y, $yi, 1;
      if ($cx eq $cy) {
        $v[$xi][$yi] = 1 + (($xi && $yi) ? $v[$xi - 1][$yi - 1] : 0);
      } else {
        $left = ($xi && $v[$xi - 1][$yi]) || 0;
        $above = ($xi && $v[$xi][$yi - 1]) || 0;
        $v[$xi][$yi] = ($left > $above) ? $left : $above; 
      }     
    }   
  } 
  return $v[length($x) - 1][length($y) - 1];
} 

##</code><code>##

sub matchss {
  my($ss, $str) = @_;
  my @state = (1, (0) x length($ss));
  my %index;
  unshift @{ $index{substr $ss, $_ - 1, 1} }, $_ for 1 .. length($ss);
  for (split //, $str) { 
    $state[$_] += $state[$_ - 1] for @{ $index{$_} || [] };
  } 
  pop @state;
}

##</code><code>##

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;
}

##</code><code>##

  $count += $seen{$_} * matchss($_, $y) for keys %seen;