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;

using ll = long long;
using ull = unsigned long long;
using ld = long double;

#define MOD 1000000007

#define rep(i, n) for(ll (i) = 0LL;(i) < (ll)(n);(i)++)
#define rep2(i, s, e) for(ll (i) = (ll)(s);(i) < (ll)(e);(i)++)
#define repi(i, n) for(ll (i) = 0LL;(i) <= (ll)(n);(i)++)
#define repi2(i, s, e) for(ll (i) = (ll)(s);(i) <= (ll)(e);(i)++)
#define per(i, n) for(ll (i) = (ll)(n) - 1LL;(i) >= 0LL;(i)--)
#define per2(i, s, e) for(ll (i) = (ll)(s) - 1LL;(i) >= (ll)(e);(i)--)
#define peri(i, n) for(ll (i) = (ll)(n);(i) >= 0LL;(i)--)
#define peri2(i, s, e) for(ll (i) = (ll)(s);(i) >= (ll)(e);(i)--)
#define iter(i, it) for(auto &(i): (it))

template<typename T, typename U> ostream& operator<<(ostream &s, const pair<T, U> m) {
    cout << "(" << m.first << ", " << m.second << ")";
    return s;
}
template<typename T, typename U> ostream& operator<<(ostream &s, const map<T, U> m) {
    ll c = 0;
    cout << "{ ";
    iter(i, m) cout << i << (c++ == m.size() - 1 ? " " : ", ");
    cout << "}";
    return s;
}
template<typename T> ostream& operator<<(ostream &s, const vector<T> &v) {
    cout << "{ ";
    rep(i, v.size()) cout << v[i] << (i == v.size() - 1 ? " " : ", ");
    cout << "}";
    return s;
}
template<typename T> ostream& operator<<(ostream &s, const list<T> &v) {
    ll c = 0;
    cout << "{ ";
    iter(i, v) cout << i << (c++ == v.size() - 1 ? " " : ", ");
    cout << "}";
    return s;
}

bool isPalindrome(string s) {
    string t = s;
    reverse(t.begin(), t.end());
    return t == s;
}

int main(void) {
    ll N;
    string S;
    cin >> S;
    N = S.size();
    if(isPalindrome(S) && isPalindrome(S.substr(0, (N - 1) / 2)) && isPalindrome(S.substr((N + 3) / 2 - 1))) {
        cout << "Yes" << endl;
    } else {
        cout << "No" << endl;
    }
    return 0;
}