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 Java7 (OpenJDK 1.7.0) (judge verdict: Accepted)

import java.util.*;
import java.math.*;

class Main{
    public static void cout(String str)
    {
        System.out.println(str);
    };
    public static void main(String args[])
    {
        Scanner cin=new Scanner(System.in);
        String a="",b="",str;
        int n;
        n=cin.nextInt();
        cin.nextLine();
        str=cin.nextLine();
        for(int i=0;i<n/2;i++)
        {
            a=a+str.charAt(i);
        }
        if(str.equals(a+a))
            cout("Yes");
        else cout("No");
    }
};