import Data.List (inits, tails)

allPartialLists :: [a] -> [[a]]
allPartialLists = filter (not . null) . concatMap inits . tails

isPalindromic :: Eq a => [a] -> Bool
isPalindromic xs = xs == reverse xs

longestPalindrome :: String -> Int
longestPalindrome s = (maximum . filter (< length s) .
    map length . filter isPalindromic . allPartialLists) s

main :: IO ()
main = print . longestPalindrome =<< getLine