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 <stdlib.h>

#undef DEBUG

void
solver(int n, char *s)
{
    int i;
    int h;
    if (n%2) {
        printf("No\n");
        return;
    }
    h = n/2;
    for (i=0; i<h; i++) {
        if (s[i]!=s[i+h]) {
            printf("No\n");
            return;
        }
    }
    printf("Yes\n");
    return;
}

int
main(int argc, char *argv[])
{
    int N;
    char S[101];
#ifdef DEBUG
#else
    scanf("%d", &N);
    scanf("%s", S);
#endif
    solver(N, S);

    return 0;
}