QOJ.ac

QOJ

Limite de temps : 1 s Limite de mémoire : 512 MB Points totaux : 100 Hackable ✓

#4274. $2x + 2$

Problème utilisé dans ces concours :

AI Translation — This statement was translated using AI and may contain inaccuracies. Please refer to the original statement if in doubt.

bobo 有 $n$ 个整数 $1, 2, \dots, n$，并用它们玩一个游戏。他想选择一个子集 $S \subseteq \{1, 2, \dots, n\}$，使得对于所有的 $x \in S$，都有 $(2x + 2) \notin S$。他现在对 $S$ 的最大大小很感兴趣。

输入格式

第一行包含一个整数 $n$ ($1 \le n < 10^{100}$)。

输出格式

输出一个整数，表示最大大小。

样例

样例输入 1

样例输出 1

样例输入 2

1000000000

样例输出 2

666666667

Editorials

ID	Type	Status	Title	Posted By	Last Updated	Actions
#168	Editorial	Open	题解	jiangly	2025-12-12 23:47:51	View

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