3. A number from 0 to 1 inclusive was written on the board. Each of the twenty-five students in the class approached the board, erased the number $x$ written there at the moment, and wrote $\frac{1}{2} \cos \pi x$ instead.

For which initial value of the number will the final result be the maximum?

If there are multiple answers, list them in any order separated by a semicolon.
Answer: $0 ; 1 \| 1 ; 0$

## Examples of writing answers:

$1 / 4$

0, $25 ; 0.5$

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