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>
#include <string.h>

int main(){
    int N;
    scanf("%d", &N);
    char str[N+1];
    fscanf(stdin, "%s", str);
    //printf("%s\n", str);
    int c = 1;
    if (N % 2 == 0){
        char str1[N/2+1];
        char str2[N/2+1];
        for (int i = 0; i < N/2; i++){
            str1[i] = str[i];
            str2[i] = str[i+N/2];
            if (str1[i] != str2[i]){
                c = 0;
                break;
            }
        }
        //printf("%s\n%s\n", str1, str2);
    } else {
        c = 0;
    }
    if (c == 1){
        printf("Yes");
    } else {
        printf("No");
    }
}