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.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int r = Integer.parseInt(sc.nextLine());
        String S = sc.nextLine();
        StringBuilder t = new StringBuilder();
        sc.close();

        if (!(r % 2 == 0)) {
            System.out.println("No");
        } else {
            for (int i = 0; i < r / 2; i++) {
                t.append(S.charAt(i));
                String sample = S.replaceFirst(t.toString(), "");
                sample = sample.replaceFirst(t.toString(), "");
                if (sample.equals("")) {
                    System.out.println("Yes");
                    return;
                }
            }
            System.out.println("No");
        }
    }

}