4.3. On the table, there is a stack of 11 magazines numbered from 1 to 11 (the top one is №1, the bottom one is №11). At 12:00, Dima and Fedia started reading the magazines, following this rule: each of them goes through the magazines from top to bottom, finds the first unread one, and takes it for themselves, while the read magazine is returned to the top of the stack; if there are no unread magazines in the stack, they wait until one appears. Dima reads each magazine for 30 minutes, while Fedia reads each for 31 minutes. In what order will the magazines be in the stack when Dima and Fedia finish reading them, if Dima was the first to take a magazine at 12:00?

## Senior League

## First Round
4.3. Solution. Note that in one and a half hours and one minute, Fedya and Dima will read the first three magazines, and they will be on top in reverse order. After this, they will no longer be used, so in the end, they will end up at the bottom in reverse order. The same will happen with the second and third sets of three magazines, but the 10th and 11th magazines will not switch places (which is not difficult to see with a simple examination). Thus, the final order will be $10,11,9,8,7,6,5,4,3,2,1$.

## Senior League

## First Round