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QOJ

Límite de tiempo: 2.0 s Límite de memoria: 256 MB Puntuación total: 100 Hackeable ✓

#7207. 异或树

Estadísticas

Edward 需要找到一棵包含 $n$ 个节点的无根树。每个节点都被分配了一个 $1, 2, \dots, n$ 之间的唯一编号。如果节点 $a$ 和节点 $b$ 之间简单路径上所有节点编号的异或和为零,则称 $(a, b)$ 为一个“好对”。如果一棵 $n$ 个节点的树中好对的数量超过 $n$ 个,则称其为“好树”。对 $(a, b)$ 和 $(b, a)$ 被视为同一个,仅计数一次。你能帮 Edward 找到这样一棵好树吗?

输入格式

输入包含一个整数 $n$。($1 \le n \le 10000$)

输出格式

如果能找到这样的树,第一行输出 Yes,否则输出 No。如果第一行输出为 Yes,则接下来输出 $n - 1$ 行,每行包含两个整数 $a$ 和 $b$,表示你所构造的好树中的一条边。

样例

样例输入 1

2

样例输出 1

No

样例输入 2

17

样例输出 2

Yes
9 8
9 11
9 13
9 15
9 16
11 10
13 12
15 14
16 17
8 1
1 5
5 4
4 6
6 7
7 2
2 3

说明

在第二个样例中,共有 18 个好对,分别是 $(1, 3), (1, 4), (1, 9), (3, 6), (3, 10), (3, 12), (3, 14), (3, 17), (4, 10), (4, 12), (4, 14), (4, 17), (5, 7), (7, 9), (8, 10), (8, 12), (8, 14)$ 和 $(8, 17)$。

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