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>
int main (){
	int x = 0;
	
	//入力層
	int N ;
	scanf("%d",&N);
	char S[N];
	scanf("%s",&S);

    //判定層
    if(N%2 == 0){
	    for(int i = 0; i < N/2 ;i++){
	   	    if(S[i] == S[N/2 + i])
			    x++;
	    }
    }
    else
        x--;
        
    //結果層
    printf("一致した文字数 = %d\n",x);
	if(x == N/2)
		printf("Yes");
	else
		printf("No");


	return 0;
}