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: Wrong Answer)

#include <bits/stdc++.h>

#include <algorithm>

using namespace std;

#define sqr(x) ((x) * (x))
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()

typedef long long ll;

const int MOD = 1000000007;
const int INF = 1000000007;
const ll INFLL = 1000000000000000007LL;

bool check(string s) {
  if (s.size() > 2) {
    string head = s.substr(0, s.size() / 2);
    string tail = s.substr(1 + (s.size() / 2), s.size() / 2);
    reverse(all(tail));
    return head == tail;
  } else if (s.size() == 2) {
    return s[0] == s[1];
  }
  return false;
}

void solve() {
  string S;
  cin >> S;
  string ans = "No";
  string head = S.substr(0, S.size() / 2);
  string tail = S.substr(1 + (S.size() / 2), S.size() / 2);
  if (check(S) && check(head) && check(tail)) {
    ans = "Yes";
  }
  cout << ans << endl;
}

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  // cout << fixed << setprecision(12);

  solve();

  return 0;
}