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# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
class abc145_b{
  public static void Main(){
    int n = int.Parse(Console.ReadLine());
    String str = Console.ReadLine();
    if(n%2 == 1){
      Console.WriteLine("No");
    }
    else{
      if(check(n,str)){
        Console.WriteLine("Yes");
      }
      else{
        Console.WriteLine("No");
      }
    }
  }
  public static bool check(int n, String s){
    for(int i=0; i<n/2; i++){
      if(s[i] != s[i+n/2]){
        return false;
      }
    }
    return true;
  }
}