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)

import qualified Data.ByteString.Char8 as BS

main = do
  s <- BS.getLine

  let n = BS.length s
      s1 = BS.take ((n-1) `div` 2) s
      s2 = BS.drop ((n-1) `div` 2 + 1) s

      checkPalindrome s i j | i >= j = True
                            | otherwise =
                              ((BS.index s i) == (BS.index s j))
                              && checkPalindrome s (i+1) (j-1)

  putStrLn $ if s1 == s2 && checkPalindrome s1 0 ((n-1) `div` 2 - 1)
             then "Yes"
             else "No"