样例输出：$3900$.
by bcbgszyzh @ 2023-05-02 14:56:14
找到一组错误数据：
```
2000 8
800 2
400 5
400 5
500 3
200 2
430 4
540 3
239 3
```
by bcbgszyzh @ 2023-05-02 15:08:16
@[bcbgszyzh](/user/726902) 这边建议lz学下背包dp，明显这道题贪心没有最优解
by hzoi_Shadow @ 2023-05-02 15:13:46
@[The_Shadow_Dragon](/user/848964)
行行行
by bcbgszyzh @ 2023-05-02 15:15:08
by bcbgszyzh @ 2023-05-08 15:50:42