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;

class B{
  public static void Main(){
    string K = Console.ReadLine();
    string fs = string.Join("", K.Reverse());
    string ss = K.Substring(0, (K.Length - 1) / 2);
    string ssr = string.Join("", ss.Reverse());
    string ts = fs.Substring(0, (K.Length - 1) / 2);
    string tsr = string.Join("", ts.Reverse());
    if (K != fs) Console.WriteLine("No");
    else if (ss != ssr) Console.WriteLine("No");
    else if (ts != tsr) Console.WriteLine("No");
    else Console.WriteLine("Yes");
  }
}