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 {
  static Scanner sc = new Scanner(System.in);
  public static void main(String[] args) {

    int len = sc.nextInt();
    // sc = new Scanner(System.in);
    String str = sc.next();

    if (len%2 == 1){System.out.println("No");return;}

    // String substr_former = str.substring(0, len/2);
    String substr_later = str.substring((len/2), len);

    if (str.startsWith(substr_later)){
      System.out.println("Yes");
    }else {
      System.out.println("No");
    }
  }
}