hack数据:(正确性已通过谷群讨论)
input 3 2 1 4 3 2 1 0 5 4 2 -3 4 -4 output 1
被叉爆的题解: https://www.luogu.com.cn/blog/zhoushengyu/solution-p1766 https://www.luogu.com.cn/blog/user51719/solution-p1766 https://www.luogu.com.cn/blog/82564/solution-p1766 (缺失了一步)