Recover Palindrome

Bob had a [palindrome](https://en.wikipedia.org/wiki/Palindrome) $P$ of length $N$ consisting of lowercase English letters, but he accidentally erased some of its characters. The resulting string $S$ has the same length $N$, where each character is either a lowercase English letter (if it was not erased) or the symbol `?` (if it was erased). Given $S$, your task is to determine whether the origin