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 PHP7 (7.0.15) (judge verdict: Wrong Answer)

<?php
  fscanf(STDIN, '%d', $n);
  fscanf(STDIN, '%s', $s);
  
  $first = substr($s, 0, $n/2);
  
  if(!empty($first)){
    $res = strpos($s, $first, $n/2);
  }
  
  if(isset($res) && $res){
      echo 'Yes'.PHP_EOL;
  } else {
      echo 'No'.PHP_EOL;
  }