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: Accepted)

<?php
  $n = trim(fgets(STDIN));
  $s = trim(fgets(STDIN));

  if ($n % 2 == 1) {
    echo 'No' . PHP_EOL;
    return;
  }

  $half = $n / 2;
  $be = substr($s, 0, $half);
  $af = substr($s, $half);
  $ans = ($be === $af) ? 'Yes' : 'No';
  echo $ans . PHP_EOL;