what is the test case it will fail?
#include <bits/stdc++.h>
#define ll long long int
using namespace std;
void solve(){
ll n,i=0,j=1,k,b,c;
cin>>n;
string s="",a;
cin>>a;
while(i<n){
if(j%2){
s+=a[i];
}
else{
s+=s;
}
j++;
i=s.size();
}
if(s==a){cout<<"YES\n";}
else{cout<<"NO\n";}
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
ll t;
cin>>t;
while(t--){solve();}
return 0;}
