UVA12123 Magnetic Train Tracks

Description

[problemUrl]: https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=243&page=show_problem&problem=3275 [PDF](https://uva.onlinejudge.org/external/121/p12123.pdf) ![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA12123/4b358a2133b38fb37f265c1f62fdec160d0f80b3.png)

Input Format

![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA12123/a35f40a5026c6c972b2fab1fe577cda029811439.png)

Output Format

![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA12123/30b2ff61e4255d461d296e1e81933b2e35de7668.png)