public function dist(&$A, &$B)
    {
        $h1 = $this->simhash($A);
        $h2 = $this->simhash($B);
        $d = 0;
        for ($i=0;$i<$this->length;$i++) {
            if ($h1[$i]!=$h2[$i])
                $d++;
        }

        return $d;
    }