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++ (GCC 9.2.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
using namespace std;
using ll=long long;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define inf 1001001001001001001
#define mod 1000000007
#define mod2 998244353
#define pi acos(-1)
#define all(v) v.begin(),v.end()
int main(){
    int N;string s;cin>>N>>s;
    string test="";
    bool flag=true;
    if(N%2==1){
        cout<<"No"<<endl;
        return 0;
    }else{
        for(int i=0;i<N/2;i++){
            test+=s.at(i);
        }
        for(int i=N/2;i<N;i++){
            if(test.at(i-N/2)!=s.at(i)){
                flag=false;
                break;
            }
        }
    }
    if(flag)cout<<"Yes"<<endl;
    else cout<<"No"<<endl;

}