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: Wrong Answer)

#include <stdio.h>
#include <string.h>
#define Fori(g) for(int i=0;i<g;i++)
#define	Forj(g) for(int j=0;j<g;j++)
#define min(aa,bb) return (aa<bb)?aa:bb
#define max(aa,bb) return (aa<bb)?bb:aa

int main(){
	int n,flag=0;
	char s[100];
	scanf("%d",&n);
	scanf("%s",s);
	int j=n/2;
	if(n==1 || n%2==1)printf("No\n");
	for(int i=0;i<n/2;i++){
		if(s[i]==s[j])flag++;
		j++;
	}
	if(flag==n/2)printf("Yes\n");
	else printf("No\n");
	return 0;
}