Summary Power

You work as an engineer. You were given an empty board with $K$ consecutive cells; at any moment, each cell can display one character. You want the board to display a string $S$ with length $N > K$. Since the board isn't large enough, you want to display the string in $N-K+1$ steps. In the $i$-th step ($1 \le i \le N-K+1$), you'll make the board display the characters $S_i, S_{i+1}, \dots, S_{i+K