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# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Linq;
using System.Collections.Generic;

namespace ABC159
{
    class B
    {
        static void Main(string[] args)
        {
            var S = Console.ReadLine();
            var s = S.Substring(0, (S.Length - 1) / 2);

            //Console.WriteLine(s);

            // check
            bool kaibun = true;
            for (int i = 0; i < s.Length / 2; i++)
            {
                if (s[i] != s[s.Length - 1 - i]) kaibun = false;
            }

            var s2 = S.Substring((S.Length + 2) / 2, S.Length / 2);
            //Console.WriteLine(s2);
            //Console.WriteLine(kaibun);
            if (kaibun && s == s2) Console.WriteLine("Yes");
            else Console.WriteLine("No");

        }
    }
}