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 <bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < (n); ++i)
using namespace std;
typedef long long ll;




    int main()
    {
        int n;
        string s;
        std::cin >> n >> s;
        int num = s.size();
        if(num%2 != 0) std::cout << "No" << "\n";
        else{
            num = num/2;
            for (int i = 0; i < num; ++i)
            {
                if (s[i] != s[i+num])
                {
                    std::cout << "No" << "\n";
                    return 0;
                }
            }
            
        }
        std::cout << "Yes" << "\n";
        return 0;
    }