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.Collections.Generic;
using System.Linq;

namespace ABCTemplate_B
{
    public class Program
    {
        static void Main(string[] args)
        {
            var b = new ProblemB();
        }
    }

    public class ProblemB
    {
        public ProblemB()
        {
            
            // 文字列の入力
            string s = Console.ReadLine();
            var wholeFlag = Check(s);

            var n = s.Length;
            var start = string.Join("", s.Take((n - 1) / 2));
            var end = string.Join("", s.Skip((n + 1) / 2));
            var startFlag = Check(start);
            var endFlag = Check(end);
            //出力
            if (wholeFlag & startFlag & endFlag)
            {
                Console.WriteLine("Yes");
            }
            else
            {
                Console.WriteLine("No");
            }
            
        }

        private bool Check(string s){
            var flag = false;
            var rev = string.Join("", s.Reverse());
            if (s == rev)
            {
                flag = true;
            }
            else
            {
                flag = false;
            }
            return flag;
        }
    }
}