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>
#define rep(i, n) for (int i=0;i<(n);i++)
using namespace std;
#define vecout(V) for(int i=0;i<V.size();i++) {cout<<V[i]<<endl;}
typedef long long ll;

int main(void){
    int n;
    cin>>n;
    string s;
    cin>>s;
    if(n%2==1){
        cout<<"No"<<endl;
    }
    else {
        int flag=0;
        rep(i, n/2){
            if(s[i]!=s[i+n/2]) {
                flag=1;
                break;
            }
        }
        if(flag==0) cout<<"Yes"<<endl;
        else cout<<"No"<<endl;
    }
    return 0;

}