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;
 
// GNU C Compiler
//template<class T> inline string toString(T x) { ostringstream sout; sout << x; return sout.str(); }
 
 
/*
--------------------------------------------
 
	type
 
--------------------------------------------
*/
using LL = long long;
using ULL = unsigned long long;
//using pair<T1, T2> = p12;
 
/*
--------------------------------------------
 
	container
 
--------------------------------------------
*/
#define PB emplace_back
#define MP make_pair 
#define SZ(a) int((a).size())
 
/*
--------------------------------------------
 
	repetition
 
--------------------------------------------
*/
#define MAX(a,b) (a>b)?a:b
#define MIN(a,b) (a>b)?b:a
#define REP(n) for(int i=0; i<n; i++)
#define REPj(n) for(int j=0; j<n; j++)
#define REPinit(a,n) for(int i=a; i<n; i++)
#define REPinitj(a,n) for(int j=a; j<n; j++)
 
//algorithm
//#define SORT(c) sort((c).begin(),(c).end())
 
/*
--------------------------------------------
 
	constant
 
--------------------------------------------
*/
//clear memory
#define CLR(a) memset((a), 0 ,sizeof(a))
 
/*
 
	Optimizer
 
*/
//#pragma GCC optimize("Ofast")


/*
 
	Utility Algorithm
 
*/
template <typename T>
void swapAlgorithm(T& a, T& b) {
    T tmp = a;
    a = b;
    b = tmp;
}

LL euclideanAlgorithm(LL a, LL b) {
    LL a_tmp = a;
    LL b_tmp = b;

    if (a_tmp > b_tmp) {
        swapAlgorithm<LL>(a_tmp, b_tmp);
    }

    LL r = a_tmp % b_tmp;
    while (r != 0) {
        a_tmp = b_tmp;
        b_tmp = r;
        r = a_tmp % b_tmp;
    }
    return b_tmp;    
}

LL getLCM(LL a, LL b) {
    return (a * b)/(euclideanAlgorithm(a, b));
}

/*
  Code
*/

int main(int argc, char const *argv[])
{
  int N;
  cin >> N;

  string S;
  cin >> S;

  if(N % 2 == 1) {
    cout << "No" << endl;
  }
  else {
    if (S.substr(0, N/2) == S.substr(N/2, N/2)) {
      cout << "Yes" << endl;
    }
    else
    {
      cout << "No" << endl;
    }
  }
  
  return 0;
}