Problem:
Score : 200 points

Problem Statement

A string S of an odd length is said to be a strong palindrome if and only if all of the following conditions are satisfied:

S is a palindrome.

Let N be the length of S. The string formed by the 1-st through ((N-1)/2)-th characters of S is a palindrome.

The string consisting of the (N+3)/2-st through N-th characters of S is a palindrome.

Determine whether S is a strong palindrome.

Constraints

S consists of lowercase English letters.

The length of S is an odd number between 3 and 99 (inclusive).

Input

Input is given from Standard Input in the following format:

S

Output

If S is a strong palindrome, print Yes;
otherwise, print No.

Sample Input 1

akasaka

Sample Output 1

Yes

S is akasaka.

The string formed by the 1-st through the 3-rd characters is aka.

The string formed by the 5-th through the 7-th characters is aka.
All of these are palindromes, so S is a strong palindrome.

Sample Input 2

level

Sample Output 2

No

Sample Input 3

atcoder

Sample Output 3

No

Solution in Haskell (GHC 7.10.3) (judge verdict: Accepted)


main :: IO()
main = do
    s <- getLine
    putStrLn $ if isStrongPalindrome s then "Yes" else "No"

isStrongPalindrome :: String -> Bool
isStrongPalindrome s = foldr (&&) True $ map isPalindrome (s : splitMid s)

isPalindrome :: String -> Bool
isPalindrome s = isSame s $ reverse s

isSame :: String -> String -> Bool
isSame [] [] = True
isSame [] [_] = False
isSame [_] [] = False
isSame (x:xs) (y:ys) = if x /= y then False else isSame xs ys

splitMid :: String -> [String]
splitMid s =
    let
        l = length s
        n = (l - 1) `div` 2
        f = take n s
        e = drop (n + 1) s
    in
    [f, e]