cf的黄题太离谱了……，和atcoder一样，搜红题有黄/绿题出现，但难度……

https://www.luogu.com.cn/problem/CF743A

https://www.luogu.com.cn/problem/CF632A

https://www.luogu.com.cn/problem/CF550A

https://www.luogu.com.cn/problem/CF463A

https://www.luogu.com.cn/problem/CF722A

有的难度只有红！！！！