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)

#define NDEBUG

#include <unordered_map>
#include <functional>
#include <algorithm>
#include <iostream>
#include <cassert>
#include <cstring>
#include <iomanip>
#include <utility>
#include <string>
#include <vector>
#include <queue>
#include <tuple>
#include <set>
#include <map>

// [0, max)
#define FOR0(var, max) for (sl (var) = 0; (var) < (max); ++(var))
// [min, max)
#define FORi(var, min, max) for (sl (var) = (min); (var) < (max); ++(var))
// [min, max)
#define FORi_INV(var, min, max) for (sl (var) = (max) - 1; (var) + 1 > (min); --(var))
#define FORITER(var, iter) for (auto (iter) = (var).begin(); (iter) != (var).end(); (iter)++)
#define FORITER_INV(var, iter) for (auto (iter) = (var).rbegin(); (iter) != (var).rend(); (iter)++)

// a < b < c
#define LTLT(a, b, c) (((a) < (b)) && ((b) < (c)))
// a <= b < c
#define LELT(a, b, c) (((a) <= (b)) && ((b) < (c)))
// a < b <= c
#define LTLE(a, b, c) (((a) < (b)) && ((b) <= (c)))
// a <= b <= c
#define LELE(a, b, c) (((a) <= (b)) && ((b) <= (c)))

#ifndef NDEBUG
#  define MASSERT(cond) m_assert(cond, __LINE__, #cond);
#else
#  define MASSERT(...)
#endif

using namespace std;

using uc = unsigned char;
using ui = unsigned int;
using ul = unsigned long long int;

using sc = signed char;
using si = signed int;
using sl = signed long long int;

using ld = long double;

void m_assert(const bool& cond, const sl& line, const char *condstr) {
  if (!cond) {
    cerr << "Assertion Failed: " << condstr << " at line " << line << endl;
    exit(1);
  }
}

static si N;
static string S;

void solve(void) {
  if (N % 2 == 1) {
    cout << "No" << endl;
    return;
  }
  FOR0(i, N / 2) {
    if (S[i] != S[i + N / 2]) {
      cout << "No" << endl;
      return;
    }
  }
  cout << "Yes" << endl;
}

int main(void) {
  cin >> N;
  cin >> S;
  solve();
  return 0;
}