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>
int main()
{
     char arr[100], a1[100], a2[100];
      int N, i, j;
      scanf("%d%s", &N, arr);
      if (N % 2 == 0)
      {
            for (i = 0; i <= (N/2 - 1); i++)
                  a1[i] = arr[i];
             a1[i] = '\0';
             for (j = N/2; j < N; j++)
                   a2[j] = arr[j];
              a2[j] = '\0';
              if (!strcmp(arr, strcat(a1, a2)))
                  printf("Yes");
              else
                   printf("No");
        }
        else
               printf("No");
         return 0;
}