$rx_4333 = qr/
(?:
    4     3     3     [3-9]
  | 4     3     [4-9] \d
  | 4     [4-9] \d    \d
  | [5-9] \d    \d    \d
)
$/x

##</code><code>##

$rx_4333 = /
(?: 4 (?: 3 (?: 3 [3-9]
              | [4-9] \d )
        | [4-9] \d \d )
  | [5-9] \d \d \d )
$/x