Binary Substring

You are given a binary string $S$ of **even** length $N$. You can perform the following operation on string $S$ any number of times: - Select two indices $i$ and $j$ where $1 \leq i \lt j \lt N$, and both $i$ and $j$ are **odd**; - Swap $S_i$ with $S_j$; - Swap $S_{i+1}$ with $S_{j+1}$. Find the **maximum** length of a **non-decreasing substring** of the string you can obtain using any (possib