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: Wrong Answer)

#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) repi(i,0,n)
#define repi(i,a,b) for(int i=int(a);i<int(b);++i)
#define rrep(i,n) rrepi(i,n,0)
#define rrepi(i,a,b) for(int i=int(a);i>int(b);--i)
#define all(x) (x).begin(),(x).end()
#define UNIQUE(v) v.erase( unique(v.begin(), v.end()), v.end() );
#define show(v) rep(i,v.size()){cout<<v[i]<<" ";}cout<<endl;
#define MOD 1000000007
#define EPS (1e-7)
#define INF (1e9)
#define PI (acos(-1))
#define SZ(x) ((int)(x).size())
#define sum(v,i) accumulate(all(v),i)
//#define int long long
using ll = long long;
int dx[4] = { 1,0,-1,0 };
int dy[4] = { 0,1,0,-1 };
template<class T>bool chmax(T& a, const T& b) { if (a < b) { a = b; return 1; } return 0; }
template<class T>bool chmin(T& a, const T& b) { if (b < a) { a = b; return 1; } return 0; }
int gcd(int a, int b) { return b ? gcd(b, a % b) : a; }//最大公約数
int lcm(int a, int b) { return a * b / gcd(a, b); }	//最小公倍数
//template <typename... Args>void IN(Args& ... args) {cin >>args;IN(args...);return;} //まとめて入力　IN(a,b,c,d...)

void Main() {
	int n; cin >> n;
	string s; cin >> s;
	int ans;
	rep(i, n / 2 - 1) {
		if (s[i] != s[i + n / 2]) {
			cout << "No";
			return;
		}
	}
	cout << "Yes";
}

signed main() {
	Main();

	return 0;
}