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.Collections.Generic;


class Program
{
    static void Main(string[] args)
    {
        string Sstr = Console.ReadLine();
        int N = Sstr.Length;
        bool answer;

        char[] S = new char[N];
        for(int i=0; i<N; i++){
            S[i] = Sstr[i];
        }

        answer = palindrome(S, N);

        if(!answer){
            Console.WriteLine("No");
        }else{
            List<char> SList = new List<char>();
            SList.AddRange(S);
            SList = SList.GetRange(0, (N-1)/2);
            answer = palindrome(SList.ToArray(), (N-1)/2);
            if(answer){
                Console.WriteLine("Yes");
            }else{
                Console.WriteLine("No");
            }
        }
    }

    static bool palindrome(char[] S, int N){
        bool pal = true;
        if(N % 2 == 1){
            for(int i=0; i<(N-1)/2; i++){
                if(S[i] != S[N-i-1]) pal = false;
            }
        }else{
            for(int i=0; i<N/2; i++){
                if(S[i] != S[N-i-1]) pal = false;
            }
        }
        return pal;
    }
}