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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)


import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc =new Scanner(System.in);
		
		int n = Integer.parseInt(sc.nextLine());
		String txt = sc.nextLine();
		
		if (n == 1 || n % 2 != 0) {
			System.out.println("No");
		}else {
			boolean stop = false;
			for (int i=0; i<n/2; ++i) {
				
				if (txt.charAt(i) != txt.charAt((n/2)+i)) {
					stop = true;
					break;
				}
			}
			System.out.println(stop ? "No" : "Yes");
		}
		
		
		sc.close();
	}

}