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: Wrong Answer)

#include<bits/stdc++.h>
using namespace std ;
vector<int>vc;
vector<int>cv;
int l,a,b;
int main ( ) {
int n ;
cin >> n ;
string s ;
cin>>s;
if ( n % 2 != 0 ){
    cout<<"No"<<endl;
    return 0;
}
else if ( n % 2 == 0){
    for(int i = 0 ; i < n/2 ; i ++ ){
        a+= s [ i ];
        b+= s[i+(n/2)];
        cout<<a<<' '<<b<<endl;
    }
    if(a==b){
        cout<<"Yes"<<endl;
        return 0;
    }
    else {
        cout<<"No"<<endl;
    }
}
}