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 C++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <iostream>
#include <string>
using namespace std;

int main(void){
    string S;
    cin >> S;
    bool ifsp = true;
    int N = S.length();
    for(int i=0; i<(N-1)/2; i++){
        if(S[i]!=S[N-i-1])ifsp=false;
    }
    if(ifsp){
        for(int i=0; i<(N-1)/4; i++){
            if(S[i]!=S[(N-1)/2-i-1])ifsp=false;
        }
    }
    if(ifsp){
        for(int i=0; i<(N-1)/4; i++){
            if(S[(N+1)/2+i]!=S[N-i-1])ifsp=false;
        }
    }
    if(ifsp){
        cout << "Yes" << endl;
    }else{
        cout << "No" << endl;
    }
    return 0;
}