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.Text;
using System.Text.RegularExpressions;
using System.Collections.Generic;

class Program
{
	//回文かを判定する関数
	static bool Checker(string s){
			string rev = new string(s.Reverse().ToArray());
			if(s == rev){
					return true;
			}else{
					return false;
			}
	}

	//Main
	static void Main(string[] args)
	{
		//読み込む
		string S = Console.ReadLine();
		int N = S.Length;

		string S2 = S.Substring(0, (N-1)/2);
		string S3 = S.Substring((N+3)/2 - 1);


		if(Checker(S) && Checker(S2) && Checker(S3)){
				Console.WriteLine("Yes");
		}else{
				Console.WriteLine("No");
		}
	}
}