Watering Grass
题目描述
[problemUrl]: https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=15&page=show_problem&problem=1323
[PDF](https://uva.onlinejudge.org/external/103/p10382.pdf)
![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA10382/388518f8e3e8ce10ab22098197e19c4149d773e6.png)
输入输出格式
输入格式
![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA10382/043b45f29e67e742e9130267198ea7bfe60d35bf.png)
输出格式
![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA10382/73a7083285137761e2b9ea258ed541ab44ff938d.png)
输入输出样例
输入样例 #1
8 20 2
5 3
4 1
1 2
7 2
10 2
13 3
16 2
19 4
3 10 1
3 5
9 3
6 1
3 10 1
5 3
1 1
9 1
输出样例 #1
6
2
-1