Critical Links

题意翻译

给出一个n个点的无向图，按顺序输出桥，多组数据。

题目描述

[problemUrl]: https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=9&page=show_problem&problem=737 [PDF](https://uva.onlinejudge.org/external/7/p796.pdf) ![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA796/ec8f587dead777bc5ee0091eca2b1b714b92fb24.png)

输入输出格式

输入格式

![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA796/c300018565c9b873a898dccee22f7d326e76df4d.png)

输出格式

![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA796/9031c12c4d851da8c17408cca56f459ffc78052b.png)

输入输出样例

输入样例 #1

8
0 (1) 1
1 (3) 2 0 3
2 (2) 1 3
3 (3) 1 2 4
4 (1) 3
7 (1) 6
6 (1) 7
5 (0)
0

输出样例 #1

3 critical links
0 - 1
3 - 4
6 - 7
0 critical links