Maximum Balanced Circle

2000ms

262144K

Description:

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.

Input:

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.

Output:

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.

Sample Input:

7
4 3 5 1 2 2 1

Sample Output:

5
2 1 1 2 3

Sample Input:

5
3 7 5 1 5

Sample Output:

2
5 5

Sample Input:

3
5 1 4

Sample Output:

2
4 5

Sample Input:

7
2 2 3 2 1 2 2

Sample Output:

7
1 2 2 2 2 3 2

Informação

Provedor Codeforces

Código CF1157F