Controversial primary school math problem: snail climbing bamboo pole
A * * * takes five days. On the first day, I climbed three meters during the day and dropped two meters at night, so I climbed one meter, so I climbed four meters in four days, and climbed three meters during the day on the fifth day, so I climbed five days. Another is to start climbing at night. It takes five days to start crawling during the day, and at night, snails are no longer afraid.