Among the products that are purchased, how many of them have never received the highest rating?
product that are purchased refers to MakeFlag = 0; never received highest rating refers to Rating! = 5


SELECT COUNT(T1.ProductID) FROM ProductReview AS T1 INNER JOIN Product AS T2 ON T1.ProductID = T2.ProductID WHERE T2.MakeFlag = 0 AND T1.Rating != 5