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>
#include<ctype.h>
int main()
{
    int n,i,j,k,count=0;
    scanf("%d",&n);
    char s[n];
    scanf("%s",&s);
    if(n==1)
    {
        printf("No");
        return 0;
    }
    for(k=0;k<n;k++)
    {
        if(isupper(s[k]))
        return 0;

        else{
        for(i=0;i<n/2;i++)
        {
        for(j=n/2;j<n;j++)
        {
            if (s[i]==s[j])
                count++;
        }
        }
        }
    }
    if (count==n/2)
        printf("Yes");
    else printf("No");
    return 0;
}