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);
    int n=sc.nextInt();
    boolean flg=true;
    if(n%2!=0){
      flg=false;
    }else{
      char[] c=sc.next().toCharArray();
      char[] a=new char[n/2];
      char[] b=new char[n/2];
      for(int i=0;i<n/2;i++){
        if(a[i]!=b[i]){
          flg=false;
          break;
        }
      }
    }
    if(flg){
      System.out.println("Yes");
    }else{
      System.out.println("No");
    }
  }
}