Another World: I Have a Wall That Can Travel Through

Fang Yuan, who resigned from a big city, returned to his hometown and unexpectedly discovered that there were two mathematical formulas on a wall at home just like those in the TV series. He jokingly wiped it off and actually traveled through time. But it was neither to the berry world nor to the cheese world, but to a secret room in a different world. There were a total of fifty people in the secret room, divided into five groups of ten people each. The rule is: 1 group of ten people in 5 groups has been marked, and the marked people do not know whether they have been marked. There is a stone platform in the secret room. You can find out how many people are marked on the stone platform, but only the number of people who are marked will not be revealed. Moreover, the stone platform can only be used once, but there is no limit to the number of people who can stand on it. Question, how to find the marked group at once? Everyone looked at each other, but Fang Yuan smiled bitterly: Isn't this a primary school math olympiad question? This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.