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: Accepted)

#include <bits/stdc++.h>
using namespace std;

#define MOD 1000000007
typedef unsigned long long ull;

int N = 0;
string S = "";

int main() {
  cin >> N >> S;

  if (N % 2 == 1) {
      cout << "No" << endl;
      return 0;
  }

  if (S.substr(0, N / 2) == S.substr(N / 2, N / 2)) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
}