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 PHP (5.6.30) (judge verdict: Accepted)

<?php
  $N=+fgets(STDIN);
$s=fgets(STDIN);
$c=$N%2;
$t=floor($N/2);
for($i=0;$i<$t;$i++)$c+=$s[$i]!=$s[$i+$t];
echo $c?No:Yes;