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

namespace AtCoder
{
	public class ABC
	{
		private const int mod = 1000000007;  // 10^9+7

		static void Main(string[] args)
		{
			//System.Diagnostics.Stopwatch sw = new System.Diagnostics.Stopwatch(); sw.Start();
			//Console.SetOut(new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false });


			string s = Console.ReadLine();
			//int x = int.Parse(Console.ReadLine());
			//long x = long.Parse(Console.ReadLine());
			//int[] vs = Console.ReadLine().Split().Select(int.Parse).ToArray();
			//long[] vs = Console.ReadLine().Split().Select(long.Parse).ToArray();


			//System.Diagnostics.Debug.WriteLine(s);
			//System.Diagnostics.Debug.WriteLine(s.Substring(0, s.Length / 2));
			//System.Diagnostics.Debug.WriteLine(s.Substring(s.Length / 2 + 1, s.Length / 2));
			if (!Check(s)) {
				Console.WriteLine("No");
				return;
			}
			if (!Check(s.Substring(0, s.Length / 2))) {
				Console.WriteLine("No");
				return;
			}
			if (!Check(s.Substring(s.Length / 2 + 1, s.Length / 2))) {
				Console.WriteLine("No");
				return;
			}
			Console.WriteLine("Yes");


			//Console.Out.Flush();
			//System.Diagnostics.Debug.WriteLine(sw.Elapsed);
		}

		static bool Check(string s)
		{
			int l = s.Length;
			for (int i = 0; i < l / 2; i++) {
				if (s[i] != s[l - 1 - i]) {
					return false;
				}
			}
			return true;
		}

	}
}