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 <unistd.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>
int main(void){
int n,i,j,a,b,c = 0;
char f[102] = {};
scanf("%d",&n);
if (n%2 == 0)
{
for (i = 1;i < n;i++)
{
    scanf("%s",&f[i]);
}
/*for(j = 1;j < n;j++)
{
    if (f[1] == f[j]){break;}
}*/
for (a = 1;a < n/2;a++)
{
    if (f[a] == f[a+(n/2)])
    {
        c += 1;
    }
    else if(f[1] == f[a] && a!=1){break;}
}
if (c == 0){printf ("No");}
else if (c == (n/2)-1)
  {printf("Yes");}
else
  {printf("No");}
}
else
  {printf("No");}
return 0;
}