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;
 
static class MainClass {

  public static void Main (string[] args) {
    //var temp = Console.ReadLine().Split(' ').Select(long.Parse);
    var S = Console.ReadLine();
    var N = S.Length;
    var ans = "No";
    if(S.SequenceEqual(S.Reverse()) && S.Substring(0, (N - 1) / 2).SequenceEqual(S.Substring(0, (N - 1) / 2).Reverse()) && S.Substring(((N + 3) / 2) - 1).SequenceEqual(S.Substring(((N + 3) / 2) - 1).Reverse())){
      ans = "Yes";
    }
    
   
    Console.WriteLine(ans);
 
  }
  
}