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>
main()
{
  int N;
  char S [N];
  char T [50];
  char TT[100];
  scanf("%d",&N);
  scanf("%s",S);
  if(N%2==0){
    strncpy(T,S,N/2);
    T[N/2]='\0';
      strcat(TT,T);
      if(S==TT){
    printf("Yes");}
    else{
      printf("No");
  }
  }
  else{
    printf("No");
  }
}