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: Accepted)

#include <stdio.h>
#include <stdlib.h>

int main(void)
{
    int i, j, n;
    char *a, b;

    scanf("%d", &n);
    n += 2;
    a = (char *)malloc((n) * sizeof(char));
    for (i = 1; i < n; i++)
    {
        scanf("%c", &b);
        a[i] = b;
    }
    if ((n & 1) != 0)
    {
        printf("No\n");
        return 0;
    }
    int k = 2;
    for (j = (n >> 1) + 1; j < n; j++)
    {
        if (a[j] != a[k])
        {
            printf("No\n");
            return 0;
        }
        k++;
    }
    printf("Yes\n");
    return 0;
}