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', $length);
fscanf(STDIN, '%s', $string);

echo solve($length, $string);
echo "\n";

function solve($len, $str) {
    if ($len % 2 !== 0) {
        return "No";
    }

    $chars = str_split($str);
    $counts = array_count_values($chars);

    foreach ($counts as $cnt) {
        if ($cnt !== 2) {
            return "No";
        }
    }

    return "Yes";
}