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 Python (3.4.3) (judge verdict: Wrong Answer)

def ret_kaibun(Str):
    lens = len(Str)
    #print(Str)
    if lens > 3:
        a = ret_kaibun(S[0:int(lens/2)])
        b = ret_kaibun(S[int((lens+3)/2-1):lens])
        if a == 1 and b == 1:
            return 1
    else:
        if not Str[0] == Str[int((lens+1)/2)]:
            return 0
        return 1
    return 0
def kaibun(S):
    for i in range(len(S)):
        if not S[i] == S[len(S)-i-1]:
            return 0
    return 1

if __name__ == '__main__':
    S = input()
    check = kaibun(S)
    if check == 0:
        print('No')
    else:
        ret = ret_kaibun(S)
        if ret == 1 and check == 1:
            print('Yes')
        else:
            print('No')