1.4t1

include <bits/stdc++.h>

define endl '\n'

using namespace std;
typedef long long ll;
bool solve(){
ll n;
cin>>n;
string str;
cin>>str;
sort(str.begin(),str.end());
priority_queue<ll,vector,greater<>> pq;
ll num=1;
for(ll i=1;i<=str.size();i++){
if(str[i-1]!=str[i]){
pq.push(num);
num=1;
}else num++;
}
ll ans=1;
if(pq.size()==1)ans=str.size();
while(pq.size()>1){
ll a=pq.top();pq.pop();
ll b=pq.top();pq.pop();
ans+=a+b;
pq.push(a+b);
}
if(ans<=n)return true;
else return false;
}
int main(){
ll t;
cin>>t;
while(t--){
if(solve())cout<<"yes"<<endl;
else cout<<"no"<<endl;
}
return 0;
}