Count Palindromes

You are given a string $S_1$. You create a new string $S_2$ by performing at most one operation. The operation involves changing an alphabet at any index to any other alphabet. Example: If $S_1=aba$ Then $S_2$ can be $bba$ / $aaa$ / $abc$ .... You need to find the number of palindromes that can be created by rearranging the letters of both strings, String $S_1$ and String $S_2$. Print the maxi