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;
using System.IO;
static class Program
{
	public static bool IsKaibun(string s) {
		return s.Substring(0,s.Length/2) == new string(s.Substring(s.Length - s.Length / 2).Reverse().ToArray());
	}

	public static void Main(string[] args)
	{
		var s = Console.In.ReadLine();
		var l = s.Length;
		var c = (l - 1) / 2;
		if (IsKaibun(s) && IsKaibun(s.Substring(0, c)) && IsKaibun(s.Substring((l+3)/2-1))) {
			Console.WriteLine("Yes");
		} else {
			Console.WriteLine("No");
		}

	}
}