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;
class Program
{
    static void Main(string[] args)
    {
        int n = int.Parse(Console.ReadLine());
        string s = Console.ReadLine();
        bool ans = false;
        if (n % 2 == 1)
        {
            goto end;
        }
        if (s.Substring(0,n/2) == s.Substring(n/2,n/2))
        {
            ans = true;
        }
        end:
        Console.WriteLine(ans ? "Yes" : "No");
        return;
    }
}