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;
using System.Collections.Generic;
using System.Linq;
using static System.Console;
using static System.Math;

namespace B_ABC145
{
    class MainClass
    {

        static int[] n;

        public static void Main(string[] args)
        {
            
            n = Array.ConvertAll(ReadLine().Split().ToArray(), int.Parse);
            string s = ReadLine();
            if(n[0]%2==1){
                WriteLine("No");
                return;
            }
            int mid = n[0]/2;
            string s1 = s.Substring(0,mid);
            string s2 = s.Substring(mid,mid);

            if(s1==s2){
                WriteLine("Yes");
                return;
            }else{
                WriteLine("No");
                return;

            }

            
        }
    }
}