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QOJ

Time Limit: 2 s Memory Limit: 512 MB Total points: 100

#8761. 另一个计数问题

统计

题目描述

给定一个 $n - 1$ 个点的无向图,点的编号为 $2 \sim n$。对于所有的 $2 \le u < v \le n$,边 $(u, v)$ 存在当且仅当 $v$ 是 $u$ 的正整数倍。定义 $f(u, v)$ 表示 $u$ 与 $v$ 是否连通:当 $u, v$ 连通时 $f(u, v) = 1$,否则 $f(u, v) = 0$。求:

$$\left(\sum_{u = 2} ^ {n - 1} \sum_{v = u + 1} ^ n f(u, v) \cdot u \cdot v\right) \bmod {998244353}$$

输入格式

从标准输入读入数据。

输入一行一个正整数 $n$。保证 $4 \le n \le 10 ^ {11}$。

输出格式

输出到标准输出。

输出一行一个非负整数表示答案。

样例

输入

4

输出

8

解释

$f(u, v) = 1$ 当且仅当 $u = 2, v = 4$,故答案为 $2 \times 4 = 8$。

样例

输入

6

输出

80

解释

所有满足 $f(u, v) = 1$ 的 $(u, v)$ 为:$(2, 3), (2, 4), (2, 6), (3, 4), (3, 6), (4, 6)$。

样例

输入

127

输出

23573971

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