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>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define FastIO      ios_base::sync_with_stdio(0);cin.tie(0),cout.tie(0)
#define pb          push_back
#define siz         100009
#define inf         1e9+8
#define mp          make_pair
#define rep(i,n)    for(int i=0;i<n;i++)
#define repo(i,m,n) for(int i=m;i<=n;i++)
#define ll          long long
#define pii         pair<int,int >
#define sc(n)       scanf("%d",&n)
#define sc2(m,n)    scanf("%d%d",&m,&n);
#define MOD         4294967296
#define fileout     freopen("output.txt","w",stdout)
#define filein      freopen("input.txt","r",stdin)
#define mem(x,i)    memset(x,i,sizeof x)
#define PI          acos(-1.0)
#define ff          first
#define ss          second
#define all(x)      x.begin(),x.end()
#define Case(t)     for(int ks=1;ks<=t;ks++)
/*------------------------------Graph Moves----------------------------*/
//const int fx[]={+1,-1,+0,+0};
//const int fy[]={+0,+0,+1,-1};
//const int fx[]={+0,+0,+1,-1,-1,+1,-1,+1};   // Kings Move
//const int fy[]={-1,+1,+0,+0,+1,+1,-1,-1};  // Kings Move
//const int fx[]={-2, -2, -1, -1,  1,  1,  2,  2};  // Knights Move
//const int fy[]={-1,  1, -2,  2, -2,  2, -1,  1}; // Knights Move
/*---------------------------------------------------------------------*/
using namespace __gnu_pbds;
using namespace std;
template <typename T>  using orderedSet =
    tree<T, null_type, less<T>,
    rb_tree_tag, tree_order_statistics_node_update>;//find_by_order,order_of_key


int main()
{
    int n;
    cin>>n;
    string str;
    cin>>str;
    for(int i=0,j=n/2;i<n/2;i++,j++)
    {
        if(str[i]!=str[j])
        {
            cout<<"No\n";
            return 0;
        }
    }
    puts("Yes");
}