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 Kotlin (1.0.0) (judge verdict: Wrong Answer)

fun main(args: Array<String>){
    var count = 0
    val r = readLine()!!.toInt()
    val s = readLine()!!.split("").filter { it != ""}
    if (r % 2 == 0) {
        var i = 0
        for ( i in i..r/2-1) {
            if (s[i] != s[r/2+i]) {
                count ++
            }
        }
        if (count == 0) {
            print("YES")
        } else {
            print("NO")
        }
    } else {
        print("NO")
    }
}