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: Accepted)

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;

class Echo
{
    static void Main(string[] args)
    {
        var number = int.Parse(Console.ReadLine());

        var input = Console.ReadLine();

        string  first ="";
        string second = "";
        var ans = "";

        for(var i = 0; i < number; i++)
        {
            if(i < number / 2)
            {
                first += input[i].ToString();
            }
            else if (number /2 <= i)
            {
                second += input[i].ToString();
            }
        }


        if(first == second)
        {
            ans = "Yes";
        }
        else
        {
            ans = "No";
        }

        Console.WriteLine(ans);
    }
}