Alternating Binary String

You are given a binary string $S$ of length $N$. You can perform the following operation on it: - Choose an index $i$ ($1 \leq i \leq N$), and *flip* **every** character of $S$ from index $i$ to $N$. Flipping a character means turning it from $0$ to $1$ and vice versa. For example, if $S = 1001101$ and you choose $i = 4$, the resulting string will be $S = 1000010$. Find the **minimum** numbe