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>

#define rep(i, n) for(int i = 0; i < (int)(n); i++)
#define repr(i, n) for(int i = (int)(n); i >= 0; i--)
#define repm(i, m, n) for(int i = (int)(m); i < (int)(n); i++)
#define repmr(i, m, n) for(int i = (int)(n); i >= (int)(m); i--)
#define all(x) (x).begin(),(x).end()
#define inf 2e9
#define MOD 1000000007

using namespace std;
typedef long long ll;

int main(){
  int n; cin >> n;
  string s; cin >> s;

  if(n%2 == 1) cout << "No";
  else if(s.substr(0, n/2) == s.substr(n/2, n/2)) cout << "Yes" << endl;
  else cout << "No";
}