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() {
    int n, flag=0;
    string s;
    cin >> n >> s;
    if (n%2==0) {
        for (int i=0; i<n/2; i++) {
            if (s[i]==s[i+n/2]) {
                flag++;
            }
        }
        if (flag==n/2) {
            cout << "Yes" << endl;
        }
        else {
            cout << "No" << endl;
        }
    }
    else {
        cout << "No" << endl;
    }
    return 0;
}