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<stdlib.h>
#include<stdio.h>
int main(){
  int N;
  char S[101];
  int i;
  scanf("%d",&N);
  scanf("%s",&S[i]);
  int a=0,b;
  b=N/2;
  if(N%2==1){
    printf("No\n");
    exit(0);
  }
  for(i=0;i<b;i++){
    if(S[i]==S[i+b]){
      a++;
    }
  }
  if(a==b){
    printf("Yes\n");
  }
  else if(a!=b){
    printf("No\n");
  }
  return 0;
}