CF868E.Policeman and a Tree

You are given a tree (a connected non-oriented graph without cycles) with vertices numbered from 1 to n, and the length of the i-th edge is w__i. In the vertex s there is a policeman, in the vertices _x_1, _x_2, ..., x__m (x__j ≠ s) m criminals are located.

The policeman can walk along the edges with speed 1, the criminals can move with arbitrary large speed. If a criminal at some moment is at the same point as the policeman, he instantly gets caught by the policeman. Determine the time needed for the policeman to catch all criminals, assuming everybody behaves optimally (i.e. the criminals maximize that time, the policeman minimizes that time). Everybody knows positions of everybody else at any moment of time.

给你一棵树（一个无环的连通无向图），其顶点编号为 $1$ 到 $n$，第 $i$ 条边的长度为 $w_i$。在顶点 $s$ 处有一名警察，在顶点 $x_1,\,x_2,\,\dots,\,x_m$（其中 $x_j \ne s$）处有 $m$ 名罪犯。

警察沿边行走的速度为 $1$，罪犯的移动速度可以任意大。若在某一时刻某名罪犯与警察处于同一位置，则该罪犯会立即被警察抓获。假设所有参与者均采取最优策略（即罪犯尽可能延长被抓时间，而警察则尽可能缩短该时间），求警察抓获所有罪犯所需的最短时间。任意时刻，所有参与者均完全知晓彼此的当前位置。

The first line contains single integer n (1 ≤ n ≤ 50) — the number of vertices in the tree. The next n - 1 lines contain three integers each: u__i, v__i, w__i (1 ≤ u__i, v__i ≤ n, 1 ≤ w__i ≤ 50) denoting edges and their lengths. It is guaranteed that the given graph is a tree.

The next line contains single integer s (1 ≤ s ≤ n) — the number of vertex where the policeman starts.

The next line contains single integer m (1 ≤ m ≤ 50) — the number of criminals. The next line contains m integers _x_1, _x_2, ..., x__m (1 ≤ x__j ≤ n, x__j ≠ s) — the number of vertices where the criminals are located. x__j are not necessarily distinct.

第一行包含一个整数 $n$（$1 \leq n \leq 50$）——树中顶点的数量。接下来的 $n-1$ 行每行包含三个整数：$u_i$、$v_i$、$w_i$（$1 \leq u_i, v_i \leq n$，$1 \leq w_i \leq 50$），表示边及其长度。保证所给图是一棵树。

下一行包含一个整数 $s$（$1 \leq s \leq n$）——警察出发的顶点编号。

下一行包含一个整数 $m$（$1 \leq m \leq 50$）——罪犯的数量。再下一行包含 $m$ 个整数 $x_1, x_2, \dots, x_m$（$1 \leq x_j \leq n$，且 $x_j \neq s$）——罪犯所在顶点的编号。这些 $x_j$ 不一定互不相同。

If the policeman can't catch criminals, print single line "Terrorists win" (without quotes).

Otherwise, print single integer — the time needed to catch all criminals.

如果警察无法抓住所有罪犯，则输出一行 “Terrorists win”（不带引号）。

否则，输出一个整数——抓住所有罪犯所需的时间。

In the first example one of the optimal scenarios is the following. The criminal number 2 moves to vertex 3, the criminal 4 — to vertex 4. The policeman goes to vertex 4 and catches two criminals. After that the criminal number 1 moves to the vertex 2. The policeman goes to vertex 3 and catches criminal 2, then goes to the vertex 2 and catches the remaining criminal.

在第一个例子中，一种最优方案如下：罪犯 2 移动到顶点 3，罪犯 4 移动到顶点 4。警察移动到顶点 4，捕获两名罪犯。随后，罪犯 1 移动到顶点 2。警察先移动到顶点 3 捕获罪犯 2，再移动到顶点 2 捕获剩余的罪犯。