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.Linq;

class A
{
    public static void Main(string[] args)
    {
        int t = 1;
        while (t > 0)
        {
            
            int n = int.Parse(Console.ReadLine());
            string s = Console.ReadLine();
            bool ok = true;
            if (n % 2 == 1)
                ok = false;
            else
            {
                int mid = n / 2;
                for(int i = 0; i < mid; i++)
                {
                    if(s[i] != s[i + mid])
                    {
                        ok = false;
                    }
                }
            }
            Console.WriteLine(ok ? "Yes" : "No");
            t--;
        }
    }
}