Palindrome Swaps

Chef has $N$ strings. Each string $S_i$ has length $M$ and consists only of lowercase english letters. Chef likes [palindromes](https://en.wikipedia.org/wiki/Palindrome), and would like each $S_i$ to be a palindrome. To achieve this, he can perform the following move: - Pick an index $i$ such that $1 \leq i \lt N$ and an index $j$ such that $1 \leq j \leq M$. - Then, swap the $j^{th}$ character o