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
  $len = intval(fgets(STDIN));
  $str = trim(fgets(STDIN));

  if($len%2==1){
    echo "No\n";
  }else{
    $str1 = substr($str, 0, $len/2);
    $str2 = substr($str, $len/2);
    
    if(strcmp($str1,$str2)==0){
      echo "Yes\n";
    }else{
      echo "No\n";
    }
  }