Sereja and Stairs

1000ms

262144K

Description:

Sereja loves integer sequences very much. He especially likes stairs.

Sequence a₁, a₂, ..., a_|a| (|a| is the length of the sequence) is stairs if there is such index i (1 ≤ i ≤ |a|), that the following condition is met:

a₁ < a₂ < ... < a_i - 1 < a_i > a_i + 1 > ... > a_|a| - 1 > a_|a|.

For example, sequences [1, 2, 3, 2] and [4, 2] are stairs and sequence [3, 1, 2] isn't.

Sereja has m cards with numbers. He wants to put some cards on the table in a row to get a stair sequence. What maximum number of cards can he put on the table?

Input:

The first line contains integer m (1 ≤ m ≤ 10⁵) — the number of Sereja's cards. The second line contains m integers b_i (1 ≤ b_i ≤ 5000) — the numbers on the Sereja's cards.

Output:

In the first line print the number of cards you can put on the table. In the second line print the resulting stairs.

Sample Input:

5
1 2 3 4 5

Sample Output:

5
5 4 3 2 1

Sample Input:

6
1 1 2 2 3 3

Sample Output:

5
1 2 3 2 1

Informação

Provedor Codeforces

Código CF381B