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", $a);
  fscanf(STDIN, "%s", $b);

if($a == 0||$a % 2 != 0) {
  echo "No";
  exit();
}

$word = explode('', $b);
$l = 0;
while($l < count($word)/2) {
  if($word[$l] !== $word[count($word-$l)]) {
    echo 'No';
    exit();
  }
  $l++;
  if($l === count($word)){
    echo 'Yes';
  }
}