The Gellar Siblings

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Monica Gellar loves to organize things. At the same time Monica has her own picky tastes and would like to include her favorite numbers 4 and 7 in her organizing / numbering system, i.e. her numbering system will consist a sequence of the numbers 4 and 7. Monica brought home a book collection s with n books. The numberings of her book collection only consists of her favorite numbers. The digits a

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solution.cppC++17

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