## 292. Math Puzzle $9 / 89$

Good resolution! This school year, we will declare war on the "fours" and the "ones of the little man" - as the unloved three is called. The final grades in mathematics from the previous year had led the students of $8 \mathrm{a}$ and $8 \mathrm{~b}$ to this plan.

None of them received a five, but every ninth student could proudly present a one, every third a two, and every sixth had to receive a four for lack of diligence. More than twenty, but fewer than forty students learn together in these parallel classes.

How many of them want to improve their three with effort in the new school year?