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Two Chess Pieces

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Description:

Cirno_9baka has a tree with $$$n$$$ nodes. He is willing to share it with you, which means you can operate on it.

Initially, there are two chess pieces on the node $$$1$$$ of the tree. In one step, you can choose any piece, and move it to the neighboring node. You are also given an integer $$$d$$$. You need to ensure that the distance between the two pieces doesn't ever exceed $$$d$$$.

Each of these two pieces has a sequence of nodes which they need to pass in any order, and eventually, they have to return to the root. As a curious boy, he wants to know the minimum steps you need to take.

Input:

The first line contains two integers $$$n$$$ and $$$d$$$ ($$$2 \le d \le n \le 2\cdot 10^5$$$).

The $$$i$$$-th of the following $$$n - 1$$$ lines contains two integers $$$u_i, v_i$$$ $$$(1 \le u_i, v_i \le n)$$$, denoting the edge between the nodes $$$u_i, v_i$$$ of the tree.

It's guaranteed that these edges form a tree.

The next line contains an integer $$$m_1$$$ ($$$1 \le m_1 \le n$$$) and $$$m_1$$$ integers $$$a_1, a_2, \ldots, a_{m_1}$$$ ($$$1 \le a_i \le n$$$, all $$$a_i$$$ are distinct)  — the sequence of nodes that the first piece needs to pass.

The second line contains an integer $$$m_2$$$ ($$$1 \le m_2 \le n$$$) and $$$m_2$$$ integers $$$b_1, b_2, \ldots, b_{m_2}$$$ ($$$1 \le b_i \le n$$$, all $$$b_i$$$ are distinct)  — the sequence of nodes that the second piece needs to pass.

Output:

Output a single integer  — the minimum steps you need to take.

Sample Input:

4 2
1 2
1 3
2 4
1 3
1 4

Sample Output:

6

Sample Input:

4 2
1 2
2 3
3 4
4 1 2 3 4
1 1

Sample Output:

8

Note:

In the first sample, here is one possible sequence of steps of length $$$6$$$.

  • The second piece moves by the route $$$1 \to 2 \to 4 \to 2 \to 1$$$.

  • Then, the first piece moves by the route $$$1 \to 3 \to 1$$$.

In the second sample, here is one possible sequence of steps of length $$$8$$$:

  • The first piece moves by the route $$$1 \to 2 \to 3$$$.

  • Then, the second piece moves by the route $$$1 \to 2$$$.

  • Then, the first piece moves by the route $$$3 \to 4 \to 3 \to 2 \to 1$$$.

  • Then, the second piece moves by the route $$$2 \to 1$$$.

Informação

Codeforces

Provedor Codeforces

Código CF1774E

Tags

dfs and similardpgreedytrees

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Datas 09/05/2023 10:35:17

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