Codeforces Round 236 (Div. 1)
E
Two Rooted Trees
Codeforces
2900
原题
← D→
翻译中…

You have two rooted undirected trees, each contains $*n*$ vertices. Let's number the vertices of each tree with integers from $1$ to $*n*$. The root of each tree is at vertex $1$. The edges of the first tree are painted blue, the edges of the second one are painted red. For simplicity, let's say that the first tree is blue and the second tree is red.

翻译中…

Edge ${*x*, *y*}$ is called bad for edge ${*p*, *q*}$ if two conditions are fulfilled:

翻译中…
  1. The color of edge ${*x*, *y*}$ is different from the color of edge ${*p*, *q*}$.
  2. Let's consider the tree of the same color that edge ${*p*, *q*}$ is. Exactly one of vertices $*x*$, $*y*$ lies both in the subtree of vertex $*p*$ and in the subtree of vertex $*q*$.
翻译中…

In this problem, your task is to simulate the process described below. The process consists of several stages:

翻译中…
  1. On each stage edges of exactly one color are deleted.
  2. On the first stage, exactly one blue edge is deleted.
  3. Let's assume that at the stage $*i*$ we've deleted edges ${*u*_{1}, *v*_{1}}$, ${*u*_{2}, *v*_{2}}$, $...$, ${*u*_{*k*}, *v*_{*k*}}$. At the stage $*i* + 1$ we will delete all undeleted bad edges for edge ${*u*_{1}, *v*_{1}}$, then we will delete all undeleted bad edges for edge ${*u*_{2}, *v*_{2}}$ and so on until we reach edge ${*u*_{*k*}, *v*_{*k*}}$.
翻译中…

For each stage of deleting edges determine what edges will be removed on the stage. Note that the definition of a bad edge always considers the initial tree before it had any edges removed.

翻译中…

Input

翻译中…

The first line contains integer $*n*$ ($2 ≤ *n* ≤ 2·10^{5}$) — the number of vertices in each tree.

翻译中…

The next line contains $*n* - 1$ positive integers $*a*_{2}, *a*_{3}, ..., *a*_{*n*}$ ($1 ≤ *a*_{*i*} ≤ *n*; *a*_{*i*} ≠ *i*$) — the description of edges of the first tree. Number $*a*_{*i*}$ means that the first tree has an edge connecting vertex $*a*_{*i*}$ and vertex $*i*$.

翻译中…

The next line contains $*n* - 1$ positive integers $*b*_{2}, *b*_{3}, ..., *b*_{*n*}$ ($1 ≤ *b*_{*i*} ≤ *n*; *b*_{*i*} ≠ *i*$) — the description of the edges of the second tree. Number $*b*_{*i*}$ means that the second tree has an edge connecting vertex $*b*_{*i*}$ and vertex $*i*$.

翻译中…

The next line contains integer $*idx*$ ($1 ≤ *idx* < *n*$) — the index of the blue edge that was removed on the first stage. Assume that the edges of each tree are numbered with numbers from $1$ to $*n* - 1$ in the order in which they are given in the input.

翻译中…

Output

翻译中…

For each stage of removing edges print its description. Each description must consist of exactly two lines. If this is the stage when blue edges are deleted, then the first line of the description must contain word $*Blue*$, otherwise — word $*Red*$. In the second line print the indexes of the edges that will be deleted on this stage in the increasing order.

翻译中…

Note

翻译中…

For simplicity let's assume that all edges of the root tree received some direction, so that all vertices are reachable from vertex $1$. Then a subtree of vertex $*v*$ is a set of vertices reachable from vertex $*v*$ in the resulting directed graph (vertex $*v*$ is also included in the set).

翻译中…

样例

Input #1
5
1 1 1 1
4 2 1 1
3
Output #1
Blue
3
Red
1 3
Blue
1 2
Red
2
InputCopy OutputCopy
题目信息
题号
403E
时间限制
4 s
内存限制
512 MB
标签
数据结构
模拟
树

题面与样例版权归 Codeforces 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。