那么下面,我将对█████'s head whether it has independent consciousness进行测试。
Hello, █████'s head。
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Problem Description
One day, several of your heads on a certain tree wanted to play a game.
Specifically, you are given a tree with $n$ nodes. Then your heads will play $m$ games on this tree:
In one game, $k$ of your heads participate, initially located at $x_1, x_2, \cdots, x_k$. For the sake of the players' mental health, it is guaranteed that all $x_i$ are distinct.
Each head has its favorite head. Surprisingly, your $i$-th head's favorite head is exactly your $(i\bmod k)+1$-th head. At every moment, all heads move toward their favorite head at a speed of $1$ edge per unit time. Note that the movement is continuous.
Now, your $(k+1)$-th head, who is watching from the side, wants to know how the game is going. It will ask you $q$ queries. Each query gives $p, t$, and you need to tell where your $p$-th head is at time $t$ (it may be on an edge; see Output Format).
Across different games, $k$ and $q$ may differ, and games are independent of each other.
Some details about the movement:
- If a head coincides with its favorite head, you may assume it will keep following its favorite head afterwards.
- If all heads gather at a single point, then all heads stop moving.
Input Format
The first line contains two integers $n, m$, representing the size of the tree and the number of games.
The next $n-1$ lines each contain two integers $u, v$, indicating there is an edge between nodes $u$ and $v$.
Then $m$ games follow, described in order:
The first line of a game contains two positive integers $k, q$, representing the number of heads and the number of queries.
The second line contains $k$ integers $x_1, x_2, \cdots, x_k$, representing the initial positions of the heads.
The next $q$ lines each contain two integers $p, t$, describing a query.
Output Format
For each game, output $q$ lines answering the queries in order.
If a head is located at node $u$, output u u (separated by a space).
If a head is located on edge $u-v$, let $u < v$, output u v (separated by a space).
Example #1
Example Input
10 2
7 6
1 4
10 7
9 2
5 7
3 7
10 9
8 6
4 10
3 2
10 2 3
1 2
1 1
4 4
9 1 8 5
4 1
3 2
3 3
1 999999993
Example Output
10 10
9 9
7 7
7 7
7 10
7 10
Constraints
For all data: $2 \le n \le 2\times 10^5$, $2 \le k \le n$, $1 \le q \le 2\times 10^5$, $\sum k, \sum q \le 4\times 10^5$, $1 \le t \le 10^9$.
Scoring
subtask 1 (13 pts): $n \le 3000$, $\sum k \le 6000$. Note that there is no guarantee on $q$.
subtask 2 (8 pts): The tree shape is random. The random process is: first generate a random permutation $a_1, a_2, \cdots, a_n$, then for each $a_i$ $(2 \le i \le n)$, randomly choose one from $a_1, a_2, \cdots, a_{i-1}$ and connect it to $a_i$.
subtask 3 (14 pts): The tree is a chain. Note that it is not guaranteed that the nodes on the chain are numbered consecutively from $1$ to $n$.
subtask 4 (8 pts): $k = 3$.
subtask 5 (8 pts): $k = 4$.
subtask 6 (17 pts): $k \le 30$.
subtask 7 (16 pts): $n \le 10^5$, $\sum k \le 2\times 10^5$.
subtask 8 (16 pts): No special constraints.