$r[0] = $t[0] == $s[0] && $t[0] == $e[0] ? 1 : 0;
   $r[1] = $t[1] == $s[1] && $t[1] == $e[1] ? 1 : 0;
   $r[2] = $t[2] == $s[2] && $t[2] == $e[2] ? 1 : 0;
   $r[3] = $t[3] == $s[3] && $t[3] == $e[3] ? 1 : 0;