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;

int main(void) {
    ios::sync_with_stdio(false);
    cin.tie(0);

    int N;
    string S;
    cin >> N >> S;
    if (N % 2 != 0)
        cout << "No\n";
    else {
        bool ans = true;
        for (int i = 0, j = N / 2; j < N; i++, j++) {
            if (S[i] != S[j]) {
                ans = false;
                break;
            }
        }
        cout << (ans ? "Yes\n" : "No\n");
    }

    return 0;
}