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

class Main{
    public static void main(String args[])throws IOException{
      try(BufferedReader br = new BufferedReader(new InputStreamReader(System.in))){
        //input
        int n = Integer.parseInt(br.readLine());;
        String str = br.readLine();

        if(n%2 != 0){
          System.out.println("No");
        }else{
          String tmp_str = str.substring(0, n/2);
          tmp_str = tmp_str + tmp_str;
          if(str.equals(tmp_str)){
            System.out.println("Yes");
          }else{
            System.out.println("No"); 
          }
        }
        
      }
    }
}