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07/12/2023 22:42:47

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Задачи

1345. Power Crisis

Ограничения: время – 1s/2s, память – 32MiB Ввод: input.txt или стандартный ввод Вывод: output.txt или стандартный вывод
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During the power crisis in New Zealand this winter (caused by a shortage of rain and hence low levels in the hydro dams), a contingency scheme was developed to turn off the power to areas of the country in a systematic, totally fair, manner. The country was divided up into N regions (Auckland was region number 1, and Wellington number 13). A number, m, would be picked "at random", and the power would first be turned off in region 1 (clearly the fairest starting point) and then in every m'th region after that, wrapping around to 1 after N, and ignoring regions already turned off. For example, if N=17 and m=5, power would be turned off to the regions in the order: 1, 6, 11, 16, 5, 12, 2, 9, 17, 10, 4, 15, 14, 3, 8, 13, 7.
The problem is that it is clearly fairest to turn off Wellington last (after all, that is where the Electricity headquarters are), so for a given N, the "random" number m needs to be carefully chosen so that region 13 is the last region selected.
Write a program that will read in the number of regions and then determine the smallest number m that will ensure that Wellington (region 13) can function while the rest of the country is blacked out.
Input will consist of the number of regions (N) with 13\ ≤\ N\ <\ 100.
Output will consist of the number m according to the above scheme.

Sample Input

17


Sample Output

7

Source: New Zealand Contest, 1992