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;

namespace abab145
{
    class Program
    {
        static void Main(string[] args)
        {
            int a;
            string b;
            a = int.Parse(Console.ReadLine());
            b = Console.ReadLine();
            
            int len = b.Length;
            var n = (len / 2)-1;
            var g = len-1;
            var c = n + 1;
            var l = len / 2;
            var str1 = b.Substring(0, l);
            var str2 = b.Substring(l,l);

            if (a >= 2 && a % 2 == 0)

                if (str1 == str2)
                {
                    Console.WriteLine("Yes");
                }
                else
                    Console.WriteLine("No");



            else
                Console.WriteLine("No");
 

        }
    }
}