P8650 [Lanqiao Cup 2017 NOI Qualifier A] Regular Expression Problem

Consider a simple regular expression: A regular expression consists only of `x`, `(`, `)`, and `|`. Xiaoming wants to find the length of the longest string that this regular expression can accept. For example, `((xx|xxx)x|(x|xx))xx` can accept the longest string `xxxxxx`, whose length is $6$.

A regular expression made up of `x()|`. The input length does not exceed $100$, and it is guaranteed to be valid.

Output the length of the longest string that this regular expression can accept.

Lanqiao Cup 2022 Provincial Contest Group A, Problem G. Translated by ChatGPT 5