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++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <iostream>
#include <fstream>
#include <string>

#define REP(i, n) for (int i = 0; i < (n); ++i)
using namespace std;

typedef long long ll;

int main()
{
   

    int n;
    cin >> n;
    string s;
    cin >> s;

    int mid = s.length() / 2;
    if (mid % 2 == 0)
    {
        cout << "No";
    }
    else
    {
        string l = s.substr(0, mid);
        
        (l + l == s) ? cout << "Yes" : cout << "No";
    }
    return 0;
}