Maximum Balanced Circle

给出一个长度为 $n$ 的序列 $a$，你可以选出序列的任意子集。记这个子集为 $b$，大小为 $k$，则需要满足 $\lvert b_i-b_{(i+1)\bmod k}\rvert \le 1$。你需要最大化 $k$ 的值，并输出选出的子集 $b$。

There are $ n $ people in a row. The height of the $ i $ -th person is $ a_i $ . You can choose any subset of these people and try to arrange them into a balanced circle. A balanced circle is such an order of people that the difference between heights of any adjacent people is no more than $ 1 $ . For example, let heights of chosen people be $ [a_{i_1}, a_{i_2}, \dots, a_{i_k}] $ , where $ k $ is the number of people you choose. Then the condition $ |a_{i_j} - a_{i_{j + 1}}| \le 1 $ should be satisfied for all $ j $ from $ 1 $ to $ k-1 $ and the condition $ |a_{i_1} - a_{i_k}| \le 1 $ should be also satisfied. $ |x| $ means the absolute value of $ x $ . It is obvious that the circle consisting of one person is balanced. Your task is to choose the maximum number of people and construct a balanced circle consisting of all chosen people. It is obvious that the circle consisting of one person is balanced so the answer always exists.

The first line of the input contains one integer $ n $ ( $ 1 \le n \le 2 \cdot 10^5 $ ) — the number of people. The second line of the input contains $ n $ integers $ a_1, a_2, \dots, a_n $ ( $ 1 \le a_i \le 2 \cdot 10^5 $ ), where $ a_i $ is the height of the $ i $ -th person.

In the first line of the output print $ k $ — the number of people in the maximum balanced circle. In the second line print $ k $ integers $ res_1, res_2, \dots, res_k $ , where $ res_j $ is the height of the $ j $ -th person in the maximum balanced circle. The condition $ |res_{j} - res_{j + 1}| \le 1 $ should be satisfied for all $ j $ from $ 1 $ to $ k-1 $ and the condition $ |res_{1} - res_{k}| \le 1 $ should be also satisfied.

7
4 3 5 1 2 2 1

5
2 1 1 2 3

5
3 7 5 1 5

2
5 5 

3
5 1 4

2
4 5 

7
2 2 3 2 1 2 2

7
1 2 2 2 2 3 2