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 Java7 (OpenJDK 1.7.0) (judge verdict: Wrong Answer)

import java.util.*;

public class Main {
    public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 入力の取得
      	int r = sc.nextInt();
      	String s = sc.next();
      	String[] p = s.split("");
      	int half = p.length / 2;
      	boolean flg = true;
      	if (p.length % 2 == 1) {
      	    System.out.println("No");
      	    return;
      	}
      	for(int i=0; i<half; i++) {
      	    if (!p[i].equals(p[half+i])) flg = false;
      	}

        if (flg) System.out.println("Yes");
      	else System.out.println("No");
    }
}