Reverse and Alternate

A **binary** string $S$ of length $N$ is said to be *almost alternating* if it can be converted into an alternating$^\dagger$ string by performing the following operation **at most once:** - Choose two indices $L$ and $R$ ($1 \leq L \leq R \leq N$). - Then, reverse the substring of $S$ from $L$ to $R$. After this operation, $S$ will look like $S_1S_2\ldots S_{L-1}S_RS_{R-1}\ldots S_{L+1}S_LS_{R+