Problem:
Score : 200 points

Problem Statement

Given are a positive integer N and a string S of length N consisting of lowercase English letters.

Determine whether the string is a concatenation of two copies of some string.
That is, determine whether there is a string T such that S = T + T.

Constraints

1 \leq N \leq 100

S consists of lowercase English letters.

|S| = N

Input

Input is given from Standard Input in the following format:

N
S

Output

If S is a concatenation of two copies of some string, print Yes; otherwise, print No.

Sample Input 1

6
abcabc

Sample Output 1

Yes

Let T = abc, and S = T + T.

Sample Input 2

6
abcadc

Sample Output 2

No

Sample Input 3

1
z

Sample Output 3

No

Solution in C# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

using System;
class moji
{
    static void Main()
    {
        int nagasa = int.Parse(Console.ReadLine());
        string input = Console.ReadLine();
        int nagasamae = nagasa / 2;
        int nagasaM = nagasamae - 1;
        int nagasaMa = nagasamae - 1;
        if (nagasa % 2 != 0)
        {
            Console.WriteLine("No");
            return;
        }
        string inputA = input.Substring(0, nagasaM);
        string inputB = input.Substring(nagasamae, nagasaMa);


        if (inputA == inputB)
        {
            Console.WriteLine("Yes");
        }
        else
        {
            Console.WriteLine("No");
        }
    }
}