Police Stations

题意翻译

给定一棵树，树上有一些点是警察局，要求所有点到最近的警察局的距离不大于d，求最多能删几条边

题目描述

Inzane finally found Zane with a lot of money to spare, so they together decided to establish a country of their own. Ruling a country is not an easy job. Thieves and terrorists are always ready to ruin the country's peace. To fight back, Zane and Inzane have enacted a very effective law: from each city it must be possible to reach a police station by traveling at most $ d $ kilometers along the roads. There are $ n $ cities in the country, numbered from $ 1 $ to $ n $ , connected only by exactly $ n-1 $ roads. All roads are $ 1 $ kilometer long. It is initially possible to travel from a city to any other city using these roads. The country also has $ k $ police stations located in some cities. In particular, the city's structure satisfies the requirement enforced by the previously mentioned law. Also note that there can be multiple police stations in one city. However, Zane feels like having as many as $ n-1 $ roads is unnecessary. The country is having financial issues, so it wants to minimize the road maintenance cost by shutting down as many roads as possible. Help Zane find the maximum number of roads that can be shut down without breaking the law. Also, help him determine such roads.

输入输出格式

输入格式

The first line contains three integers $ n $ , $ k $ , and $ d $ ( $ 2<=n<=3·10^{5} $ , $ 1<=k<=3·10^{5} $ , $ 0<=d<=n-1 $ ) — the number of cities, the number of police stations, and the distance limitation in kilometers, respectively. The second line contains $ k $ integers $ p_{1},p_{2},...,p_{k} $ ( $ 1<=p_{i}<=n $ ) — each denoting the city each police station is located in. The $ i $ -th of the following $ n-1 $ lines contains two integers $ u_{i} $ and $ v_{i} $ ( $ 1<=u_{i},v_{i}<=n $ , $ u_{i}≠v_{i} $ ) — the cities directly connected by the road with index $ i $ . It is guaranteed that it is possible to travel from one city to any other city using only the roads. Also, it is possible from any city to reach a police station within $ d $ kilometers.

输出格式

In the first line, print one integer $ s $ that denotes the maximum number of roads that can be shut down. In the second line, print $ s $ distinct integers, the indices of such roads, in any order. If there are multiple answers, print any of them.

输入输出样例

输入样例 #1

6 2 4
1 6
1 2
2 3
3 4
4 5
5 6

输出样例 #1

1
5

输入样例 #2

6 3 2
1 5 6
1 2
1 3
1 4
1 5
5 6

输出样例 #2

2
4 5 

说明

In the first sample, if you shut down road $ 5 $ , all cities can still reach a police station within $ k=4 $ kilometers. In the second sample, although this is the only largest valid set of roads that can be shut down, you can print either 4 5 or 5 4 in the second line.

题意翻译

给定一棵树，树上有一些点是警察局，要求所有点到最近的警察局的距离不大于d，求最多能删几条边