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;
const int INF = 1001001001;

int main() {
int N;
string S;
cin >> N >> S;
bool ans = true;
if (N % 2 != 0) ans = false;
else {
for (int i = 0;i < N/2;i++) {
if (S.at(i) != S.at(i+N/2)) ans = false;
}
}
if (ans == false) cout << "No" << endl;
else cout << "Yes" << endl;
return 0;
}