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;

#define pb push_back
#define fi first
#define se second
typedef long long ll;

int main()
{
	ios_base::sync_with_stdio(false); cin.tie(NULL);

	int n;
	string s;
	cin >> n >> s;
	if (n & 1) {
		cout << "No\n";
		return 0;
	}

	bool ok = 1;
	for (int i = 0; i < n / 2; ++i)
		if (s[i] != s[i + n / 2])
			ok = 0;
	cout << (ok ? "Yes\n" : "No\n");
}