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 (Clang 3.8.0) (judge verdict: Accepted)

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cassert>
#include<cmath>
#include<vector>
#include<map>
#include<set>
#include<string>
#include<queue>
#include<stack>

using namespace std;

#define MOD 1000000007
#define MOD2 998244353
#define INF ((1<<30)-1)
#define LINF (1LL<<60)
#define EPS (1e-10)
typedef long long ll;
typedef pair<ll, ll> P;

int main() {
    string S;
    int size;
    cin >> S;
    size = S.length();
    string front = S.substr(0, (size-1)/2);
    string rear = S.substr(size - (size-1)/2, size - 1);
    reverse(rear.begin(), rear.end());
    if(front != rear) {
        cout << "No" << endl;
        return 0;
    }
    if(front.length() == 1) {
        cout << "Yes" << endl;
        return 0;
    }
    size = front.size();
    string front_f = front.substr(0, (size-1)/2);
    string front_r = front.substr(size - (size-1)/2, size - 1);
    reverse(front_r.begin(), front_r.end());
    if(front_r.length() == 0 || front_f != front_r) {
        cout << "No" << endl;
        return 0;
    }

    size = rear.length();
    string rear_f = rear.substr(0, (size-1)/2);
    string rear_r = rear.substr(size - (size-1)/2, size - 1);
    reverse(rear_r.begin(), rear_r.end());
    if(rear_f.length() == 0 || rear_f != rear_r) {
        cout << "No" << endl;
        return 0;
    }
    cout << "Yes" << endl;
    
    return 0;
}