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;

public class Test
{
	public static void Main()
	{
		// my code goes here
		
		int n = int.Parse(Console.ReadLine());
		string s = Console.ReadLine();
		string a;
		string b;
		
		
		if(n%2==1){
			Console.WriteLine("No");
		}else{
			a = s.Substring(0,n/2);
			b = s.Substring(n/2,n/2);
			
			if(a==b){
				Console.WriteLine("Yes");
			}else{
				Console.WriteLine("No");
			}
			
		}
		
		
	}
}