Halfway through the school holidays, the naughty boys stuck a piece of paper on a friend's back with the words "I am stupid" and everyone swore that no one would tell the boy anything.

The whole class looked at the child and tasted for a long time, but no one told him anything, so two or three periods passed.

After a while, the math class started.
The math teacher wrote a very difficult question on the board. Many children tried but could not solve any...