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 <iostream>

using namespace std;

int str_length(const char s[])
{
	int len = 0;
	while(s[len])
		len++;
	return len;
}

int main()
{
	int i;
	char S[100];

	cin >> S;
	if(str_length(S) % 2 == 0 || str_length(S) > 99)
	{
		cout << "No";
		return 0;
	}

	for(i = 0; i < (str_length(S) - 1)/2; i++)
	{
		if(S[i] != S[(str_length(S) - 1)/2 - 1 - i] || S[(str_length(S) + 3)/2 - 1 + i] != S[str_length(S) - 1 - i])
		{
			cout << "No";
			return 0;
		}
	}

	cout << "Yes";
	return 0;
}