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;
 
namespace Sample
{
  class Sample
  {
    static void Main(string[] args)
    {
    int N=int.Parse(Console.ReadLine());
      string S=Console.ReadLine();
      string ans1=S.Substring(0,(N/2));
      string ans2=S.Substring((N/2),(N/2));
      if((N>=2)&&(ans1==ans2)){
        Console.WriteLine("Yes");
      }else{
        Console.WriteLine("No");
      }
    }
    
  }

}