An inspection opening of a cylindrical pressure vessel is being designed. A colleague has already calculated the missing area A, which equals 3,352mm2, and the spare metal areas A1 to A4, which are 1,953mm2, 386mm2, 135mm2, 114mm2, respectively. If the thickness of the reinforcing ring is 7mm, determine the required width of the ring. Please provide your answer in mm. If a reinforcing ring is not necessary, please let your answer be 0; otherwise, please round up your answer to the closest whole millimetre.

For example, if an answer is 3.2mm, the rounded-up value will be 4mm. Choosing 3mm would mean rounding down.