Mark Points

There are $N$ equi-spaced points numbered $1, 2, \ldots, N$. Initially, all points are unmarked. In one operation, you can choose $X$ such that $1 < X < N$, and then mark points $X - 1, X, X + 1$. (If any of them were already marked, they do not get affected) Finally, you will make a binary string $S$, where $S_i = 1$ if and only if you marked point $i$, and otherwise $S_i = 0$. --- Now, you