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;
using ll = long long;
using p = pair<int, int>;
#define INF 1001001001
#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
#define repX(i, n ,x) for (int i = x; i < (int)(n); ++i)
#define repBack(i, n) for (int i = n; i >= 0; --i)
#define dup(x,y) (((x)+(y)-1)/(y))

int main() {
    int N;
    string S;
    cin >> N >> S;
    bool flag = true;
    if(N%2==1){
        cout << "No" << endl;
        return 0;
    }
    rep(i,N/2){
        if(S[i]!=S[N/2+i])flag = false;
    }
    if(flag)cout << "Yes" << endl;
    else cout << "No" << endl;
    
    return 0;
}