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;
using ll = long long;
using P = pair<int, int>;

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

  bool ans = true;
  if (N % 2 == 1) {
    ans = false;
  }
  else {
    for (int i = 0; i < N/2; i++) {
      if (S[i] != S[i + N/2]) {
        ans = false;
        break;
      }
    }
  }
  cout << (ans ? "Yes" : "No") << endl;
}