UVA615 Is It A Tree?

Description

[problemUrl]: https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=8&page=show_problem&problem=556 [PDF](https://uva.onlinejudge.org/external/6/p615.pdf) ![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA615/09232b1e5f9c9a5e77d5b78560d175bb93bf5c18.png)

Input Format

![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA615/60285505af32b8ec29303e8a7354cdddd1dc56f3.png)

Output Format

![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA615/5a1b5aaafd7cfe3f9593adc4426723d7944d66a9.png)