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>
#include <math.h>

int main()
{
    int N;
    int num;
    int half;
    int rtn;
    char S[100+1] = {0};
    char T[50+1] = {0};
    char TT[100+1] = {0};

    if(scanf("%d", &N) == 1);
    if(scanf("%s", S) == 1);

    num = N % 2;

    if (num == 1) {
        printf("No");
        return(0);
    } else {
        half = N / 2;
        strncpy(T, S, half);
        strcat(TT, T);
        strcat(TT, T);

        rtn = strcmp(S, TT);
        if(rtn == 0){
            printf("Yes");
        } else {
            printf("No");
        }
    }

    return(0);
}