# LCA - Lowest Common Ancestor

## 题意翻译

## Description:
一棵树是一个简单无向图，图中任意两个节点仅被一条边连接，所有连通无环无向图都是一棵树。-Wikipedia
最近公共祖先（LCA）是……（此处省去对LCA的描述），你的任务是对一棵给定的树$T$以及上面的两个节点$u,v$求出他们的$LCA$。
![](https://cdn.luogu.org/upload/vjudge_pic/SP14932/0b23f0487b06b8d674d23253a6db517f49ca3acf.png)
**例如图中$9$和$12$号节点的$LCA$为$3$号节点**
## Input:
输入的第一行为数据组数$T$，对于每组数据，第一行为一个整数$N(1\leq N\leq1000)$，节点编号从$1$到$N$，接下来的$N$行里每一行开头有一个数字$M(0\leq M\leq999)$，$M$为第$i$个节点的子节点数量，接下来有$M$个数表示第$i$个节点的子节点编号。下面一行会有一个整数$Q(1\leq Q\leq1000)$，接下来的$Q$行每行有两个数$u,v$，输出节点$u,v$在给定树中的$LCA$。
输入数据保证只有一个根节点并且没有环。
## Output:
对于每一组数据输出$Q+1$行，第一行格式为"Case i:"（没有双引号），i表示当前数据是第几组，接下来的$Q$行每一行一个整数表示一对节点$u,v$的$LCA$。
## Sample Input:
```
1
7
3 2 3 4
0
3 5 6 7
0
0
0
0
2
5 7
2 7
```
## Sample Output:
```
Case 1:
3
1
```
Translated by @_yxl_gl_

## 题目描述

A tree is an undirected graph in which any two vertices are connected by exactly one simple path. In other words, any connected graph without cycles is a tree. - Wikipedia
The lowest common ancestor (LCA) is a concept in graph theory and computer science. Let T be a rooted tree with N nodes. The lowest common ancestor is defined between two nodes v and w as the lowest node in T that has both v and w as descendants (where we allow a node to be a descendant of itself). - Wikipedia
Your task in this problem is to find the LCA of any two given nodes v and w in a given tree T.
### ![](https://cdn.luogu.com.cn/upload/vjudge_pic/SP14932/0b23f0487b06b8d674d23253a6db517f49ca3acf.png)
**For example the LCA of nodes 9 and 12 in this tree is the node number 3.**
### Input
The first line of input will be the number of test cases. Each test case will start with a number N the number of nodes in the tree, 1 <= N <= 1,000. Nodes are numbered from 1 to N. The next N lines each one will start with a number M the number of child nodes of the Nth node, 0 <= M <= 999 followed by M numbers the child nodes of the Nth node. The next line will be a number Q the number of queries you have to answer for the given tree T, 1 <= Q <= 1000. The next Q lines each one will have two number v and w in which you have to find the LCA of v and w in T, 1 <= v, w <= 1,000.
Input will guarantee that there is only one root and no cycles.
### Output
For each test case print Q + 1 lines, The first line will have “Case C:” without quotes where C is the case number starting with 1. The next Q lines should be the LCA of the given v and w respectively.
### Example
```
Input:
1
7
3 2 3 4
0
3 5 6 7
0
0
0
0
2
5 7
2 7
Output:
Case 1:
3
1
```

## 输入输出格式

### 输入格式

### 输出格式

## 输入输出样例

*暂无测试点*