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<iostream>
#include<vector>
#include<string>
#include<algorithm>
#include<utility>
#include<cmath>
#include<climits>
#include<queue>
#include<stack>
#include<numeric>
#include<tuple>
using namespace std;


typedef pair<int, int> P;
typedef long long ll;

#define rep(i,n) for(int (i)=0;(i)<(n);(i)++)

ll gcd(ll a, ll b) { return b?gcd(b,a%b):a;}
ll lcm(ll a, ll b) { return a/gcd(a,b)*b;}

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

	string left, right;

	rep(i, n / 2){
		left += s[i];
	}

	for(int i = n / 2; i < n; ++i) {
		right += s[i];
	}

	if(left == right){
		cout << "Yes" << endl;
	} else {
		cout << "No" << endl;
	}
}