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>

int main(void){

  int n;
  scanf("%d", &n);
  char s[n+1];
  scanf("%s", s);

  int flag = 0;
  if (n % 2 == 0) {
    flag = 1;
    for (int i = 0; i < n/2; i++) {
      if (s[i] != s[i+n/2]) {
        flag = 0;
        break;
      }
    }
  }

  if (flag == 1) {
    printf("Yes\n");
  } else {
    printf("No\n");
  }

  return 0;
}