#include<bits/stdc++.h>
#define ll long long int
#define fab(a,b,i) for(int i=a;i<b;i++)
#define db double
#define endl "\n"
#define f first
#define se second
#define MOD 1000000007
#define quick ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)
using namespace std;
void solve(){
// int n,k;
// cin>>n>>k;
// int arr[n];
// ll pro=1;
// for(int i=0;i<n;i++){
// cin>>arr[i];
// pro*=arr[i];
// }
// int ans=pro%k;
// if(ans==0){
// cout<<0<<endl;
// }
// else{
// k-=ans;
// cout<<k<<endl;
// }
int n,k;
cin>>n>>k;
string s;
cin>>s;
int count=0;
unordered_map<char,int> mp;
for(int i=0;i<n;i++){
mp[s[i]]++;
}
for(auto itr:mp){
if(itr.second & 1){
count++;
}
}
count--;
if(k<count){
cout<<"no"<<endl;
}
else{
cout<<"yes"<<endl;
}
}
int main()
{
ll t;
cin>>t;
while(t--)
{
solve();
}
}
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