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(void){
    int N;
  	scanf("%d %*c", &N);

    char S[N];
    fgets(S, N, stdin);

    if(N%2 == 1) {
        printf("No");
        return 0;
    }

    int ans = 1;
    for(int i=0; i< N/2 -1; i++){
        if(S[i] != S[i+N/2]){
            ans = 0;
            break;
        }
    }

    if(ans == 1){
        printf("Yes");
    }else{
        printf("No");
    }

    return 0;
}