Expected Change

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Chef has a string $A$ with length $N$. It contains only characters '(', ')' and '*'. Chef wants to perform the following process: - Uniformly randomly choose a pair of integers $(l, r)$ such that $1 \le l \le r \le N$. - Consider the substring $S = [A_l, A_{l+1}, \ldots, A_r]$. Process the characters of this string from left to right. - Let's denote the current number of closing brackets in $S$

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solution.cppC++17

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