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 (GCC 5.4.1) (judge verdict: Runtime Error)

#include<stdio.h>
#include<string.h>
#include<math.h>

int main(void) {
	int n,m,i,a=0;
	char s[100];

	scanf("%d", &n);
	scanf("%s", s);
	if ((n % 2) == 1) {
		printf("No");
		return 1;
	}
	else {
		m = n / 2;
		for (i = 0; i < m; i++) {
			if (s[i] != s[i + m]) {
				++a;
			}
		}
			if (a == 0) printf("Yes");
			else printf("No");
	}
	
	return 0;
}