<Direction-Performance>


<Solution-Explanation>
[youku for Chinese]

▼ Performance
https://v.youku.com/v_show/id_XNDMzMjg1NjQ4MA==.html?spm=a2h3j.8428770.3416059.1
▼ Explanation
https://v.youku.com/v_show/id_XNDMzMjkwMDgzNg==.html?spm=a2h3j.8428770.3416059.1