Substring Strategy

*This problem has subtasks.* Alice and Bob are playing a game with a binary string $S$ of length $N$. The game involves two steps: - Alice's Move: Alice can remove any single substring from $S$. The remaining parts of the string stay in the same order. - Bob's Move: After Alice's move, Bob can select any substring of the modified string and flip all its characters. Flipping $S_i$ means it becom