A14690. Maximum Adjacent Pairs

You are given an array $a$ consisting of $n$ non-negative integers.

You have to replace each $0$ in $a$ with an integer from $1$ to $n$ (different elements equal to $0$ can be replaced by different integers).

The value of the array you obtain is the number of integers $k$ from $1$ to $n$ such that the following condition holds: there exist a pair of adjacent elements equal to $k$ (i. e. there exists some $i \in [1, n - 1]$ such that $a_i = a_{i + 1} = k$ ). If there are multiple such pairs for some integer $k$ , this integer is counted in the value only once.

Your task is to obtain the array with the maximum possible value.

The first line contains one integer $n$ ( $2 \le n \le 3 \cdot 10^5$ ) — the number of elements in the array.

The second line contains $n$ integers $a_1, a_2, \dots, a_n$ ( $0 \le a_i \le \min(n, 600)$ ) — the elements of the array.

Print $n$ integers not less than $1$ and not greater than $n$ — the array with the maximum possible value you can obtain.

If there are multiple answers, print any of them.