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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.io.*;
import java.util.*;

public class Main {
    static final String YES = "Yes";
    static final String NO = "No";

    public static void main(final String[] args) throws Exception {
        final Scanner sc = new Scanner(System.in);
        long N;
        N = sc.nextLong();
        String S;
        S = sc.next();

        final Solver solver = new Solver();
        System.out.println(solver.solve(N, S) ? YES : NO);
    }
}

class Solver {
    public boolean solve(long N, String S) {
        if (N % 2 != 0) return false;

        String first = S.substring(0, (int) N/2);
        String second = S.substring((int) (N/2));

        return first.equals(second);
    }
}