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: Wrong Answer)

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

namespace CP
{
    class Atria
    {
        static void Main(string[] args)
        {
            int n = int.Parse(ReadLine());
            string s = ReadLine();
            if (n == 1) { WriteLine("No"); return; }
            if (n % 2 == 0)
            {
                var tmp = s.Substring(0, n / 2);
                var hoge = s.Substring(n/2, n / 2);
                WriteLine(
                    tmp == hoge ? "Yes":"No"
                    );
            }
            else
            {
                var tmp = s.Substring(0, n / 2);
                var hoge = s.Substring((n / 2)+1, n / 2);
                WriteLine(
                    tmp == hoge ? "Yes" : "No"
                    );
            }
        }
    }
}