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 Java (OpenJDK 11.0.6) (judge verdict: Accepted)

import java.util.*;
public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        String s = sc.next();
        sc.close();
        boolean sa = false;
        boolean sine = false;
        if(n % 2 != 0){
            System.out.println("No");
            sine = true;
        }else{
            int[] a = new int[n / 2];
            int[] b = new int[n / 2];
            for(int i = 0 ; i < n / 2 ; i++ ){
                a[i] = s.charAt(i);
                b[i] = s.charAt(i + n / 2);
                if(a[i] != b[i]){
                    sa = true;
                }
            }
        }
        if(sa == true){
            System.out.println("No");
        }else if(sine == false){
            System.out.println("Yes");
        }
    }
}