there is an exam. professor: there are 500 bricks on board the plane. one brick fell out of the plane. How many bricks are left on board? student: well, that's easy! 499! professor: right. next question. how to put an elephant in the refrigerator in 3 steps? student: 1. open the refrigerator, 2. put the elephant in there. 3. close the refrigerator! professor: further. how to put deer in the refrigerator in four steps? student: 1. open the refrigerator. 2. pull out the elephant. 3. put the deer. 4. close the refrigerator! professor: great! next question. It's the birthday of the king of beasts, lion! All the animals came except one. Why? student: because the deer is still in the refrigerator! professor: great! Further. can granny walk through a swamp with crocodiles? student: of course he can! After all, all the crocodiles are at the lion's birthday! professor: good! and now the last question. Granny walked through an empty swamp, but still died! what happened to her? student: uh! did she drown? professor: but no! A brick fell on her, which fell out of the plane! for a "retake"!