BZOJ.4212.神牛的养成计划(Trie 可持久化Trie)
给定$n$个串，$m$次询问，每次询问给定两个串$S_1,S_2$，求$n$个串中有多少个串满足$S_1$是它的前缀且$S_2$是它的后缀。
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很久以前的奇怪但现在依旧成立的签名
attack is our red sun $$\color{red}{\boxed{\color{red}{attack\ is\ our\ red\ sun}}}$$ ------------------------------------------------------------------------------------------------------------------------
很久以前的奇怪但现在依旧成立的签名
attack is our red sun $$\color{red}{\boxed{\color{red}{attack\ is\ our\ red\ sun}}}$$ ------------------------------------------------------------------------------------------------------------------------
