while($s=~/(\w\w+)(?=.*?\1)/g)
{
        foreach $x (0..length $1) {
                map {
                        $y = substr $1, $x, $_;
                        $saw{$y}++ || do {
                                local pos $s = 0;
                                my $c=()= $s=~/\Q$y/g;
                                print "$y => $c\n";
                        }
                } ($x+1..length $1)
        }
        pos($s) = pos($s) +1 -length $1; # fix
}