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 = (int)trim(fgets(STDIN));
$s = trim(fgets(STDIN));

if ($n % 2 === 1) {
	echo 'No';
	exit();
}
$half = (int)($n/2);
for ($i=0; $i < $half; $i++) { 
	$mae = $s[$i];
	$ura = $s[$i+$half];
	if ($mae !== $ura) {
		echo 'No';
		exit();
	}
}
echo 'Yes';