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 <bits/stdc++.h>
using namespace std;

int main(){
    string S;
    cin >> S;
    int N = S.size();
    bool flag = true;
    for(int i=0,j=N-1;i<j;i++,j--) if(S[i] != S[j]) flag = false;
    if (flag) for(int i=0, j=(N-1)/2-1;i<j;i++,j--) if(S[i]!=S[j]) flag = false;
    if (flag) for(int i=(N+3)/2-1, j=N-1;i<j;i++,j--) if(S[i]!=S[j]) flag = false;
    cout << (flag ? "Yes" : "No") << endl;
}