Christina has a rooted tree with $$$n$$$ vertices. Initially, all vertices are colored green, except for the root, which is colored red. Christina thinks that the tree is beautiful if two rules are satisfied:
Christina repeatedly performs the following operation on the tree — chooses a vertex and changes its color (if it was red, colors it green; if it was green, colors it red). The following rules must be satisfied while performing the operations:
Your task is to help Christina build the longest possible sequence of operations following the rules.
The first line contains an integer $$$n$$$ ($$$1 \le n \le 20$$$) — the number of vertices in the tree.
The second line contains $$$n - 1$$$ integers $$$p_i$$$ ($$$1 \le p_i \le i$$$ for $$$1 \le i \le n - 1$$$), denoting parent vertices in the tree. The vertices in the tree are numbered from $$$1$$$ to $$$n$$$, the root has number $$$1$$$, the $$$i$$$-th vertex has parent $$$p_{i-1}$$$ for $$$2 \le i \le n$$$.
On the first line output an integer $$$m$$$ — the maximum number of operations.
On the second line output $$$m$$$ integers $$$o_i$$$ ($$$2 \le o_i \le n)$$$. $$$o_i$$$ is the number of the vertex that changes color during the corresponding operation.
If there are several possible longest sequences, output any one of them.
4 1 1 1
7 4 3 4 2 4 3 4
4 1 2 3
3 2 3 4
6 1 1 2 2 2
17 3 2 3 6 3 5 3 6 3 4 3 6 3 5 3 6 3
5 1 2 1 1
11 5 4 5 2 5 4 5 3 5 4 5
5 1 1 2 3
8 3 5 2 5 3 4 3 5