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class Solution:
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    def preimageSizeFZF(self, k: int) -> int:
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        def atMost_k(k: int) -> int:
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            left, right = 0, 5 * k + 4
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            while left <= right:
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                mid = (left + right) // 2
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                count, n = 0, mid
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                while n:
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                    n //= 5
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                    count += n
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                if count <= k:
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                    left = mid + 1
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                else:
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                    right = mid - 1
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            return right
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        return atMost_k(k) - atMost_k(k - 1)