P6492 [COCI 2010/2011 #6] STEP

Given a character sequence $a$ of length $n$, initially all characters in the sequence are `L`. There are $q$ modifications. Each time, an integer $x$ is given. If $a_x$ is `L`, then change $a_x$ to `R`; otherwise change $a_x$ to `L`. For a string $s$ consisting only of `L` and `R`, if there are no consecutive `L` and `R` in it, then $s$ is considered to satisfy the requirement. After each modification, output the length of the longest contiguous substring in the current sequence $a$ that satisfies the requirement.

The first line contains two integers, representing the length of the sequence $n$ and the number of modification operations $q$. The next $q$ lines each contain one integer, representing the position $x$ to be modified in this operation.

For each modification operation, output one integer per line, representing the length of the longest substring in the sequence $a$ that satisfies the requirement.

#### Constraints For all testdata, it is guaranteed that $1 \leq n, q \leq 2 \times 10^5$, $1 \leq x \leq n$. #### Notes **This problem is translated from [COCI2010-2011](https://hsin.hr/coci/archive/2010_2011/) [CONTEST #6](https://hsin.hr/coci/archive/2010_2011/contest6_tasks.pdf) *T5 STEP***. Translation by @[一扶苏一](https://www.luogu.com.cn/user/65363). Translated by ChatGPT 5