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 C (Clang 3.8.0) (judge verdict: Runtime Error)

#include <stdio.h>

int solve(int N, char s[]) {
    for (int i = 0; i < N / 2; i++)
        if (s[i] != s[i + N / 2])
            return 0;
    return 1;
}

int main() {
    int N;
    char s[N];
    scanf("%d\n%s", &N, s);
    printf("%s\n", solve(N, s) ? "YES" : "NO");
}