How Many Points of Intersection?

题目描述

[problemUrl]: https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=19&page=show_problem&problem=1731 [PDF](https://uva.onlinejudge.org/external/107/p10790.pdf) ![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA10790/d59a93dc3ec191ca3d549a4fc4feb0160c78ff73.png)

输入输出格式

输入格式


![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA10790/ce4ba87f7dc43f1693a9f144e7254bbd957b625a.png)

输出格式


![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA10790/38b97434fa85f7ee11020be9369e9de5ef621225.png)

输入输出样例

输入样例 #1

2 2
2 3
3 3
0 0

输出样例 #1

Case 1: 1
Case 2: 3
Case 3: 9