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;

bool provera(string s,int x,int y)
{
    while(x<y && s[x]==s[y])
    { x++; y--; }

    if(x>=y)
        return true;
    else
        return false;
}

int main()
{
	ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
    string s;
    int n;
    cin >> s; n=s.size();
    if(provera(s,0,n-1) && provera(s,0,(n-1)/2-1) && provera(s,(n+3)/2-1,n-1))
        cout << "Yes";
    else
        cout << "No";
}