1800B.cpp

#include<bits/stdc++.h>
#define ll long long
#define fast ios_base::sync_with_stdio(false);cin.tie(NULL);

#define fi(n) for(ll i=0; i<n; i++)
#define fj(n) for(ll j=0; j<n; j++)
#define rfi(n) for(ll i = n-1; i >=0; --i)
#define fa(n) for(auto i:n)
#define fa2(n) for(auto i:n) cout<<i<<' ';
#define llt ll t; cin>>t; while(t--)
#define lln ll n; cin>>n;
#define llnm ll n,m; cin>>n>>m;
#define llx ll x; cin>>x;
#define llxy ll x,y; cin>>x>>y;
#define llab ll a,b; cin>>a>>b;

#define vi vector<int>
#define vll vector<ll>
#define vs vector<string>
#define pb push_back
#define mp make_pair
#define pbx ll xx; cin>> xx; v.pb(xx);
#define pbs string xx; cin>> xx; v.pb(xx);
#define all(x) x.begin(), x.end()
#define srt(x) sort(all(x))
#define rsrt(x) sort(all(x),greater<ll>())
#define veccin(n) vll v(n); fi(n) cin>>v[i];

#define gcd(a, b) __gcd(a, b)
#define lcm(a, b) ((a)*((b)/__gcd(a,b)))

#define endl "\n"
#define nl <<endl
#define sp <<' '
#define sps <<' '<<
#define yes cout<<"YES"<<endl
#define no cout<<"NO"<<endl
#define C(x) cout<< x <<endl;
#define F i.first
#define S i.second
// ll arr[100000000]={0};

using namespace std;
int main(){
    llt{
    	ll n,k; cin>>n>>k;
    	string s; cin>>s;
    	std::map<char, ll> mp;
    	ll coin=0;
    	fi(n){
    		mp[s[i]]++;
    		if(s[i]>='A' && s[i]<='Z'){
    			if(mp[s[i]+32]>0){
    				coin++;
    				mp[s[i]+32]--;
    				mp[s[i]]--;
    			}
    		}
    		else{
    			if(mp[s[i]-32]>0){
    				coin++;
    				mp[s[i]-32]--;
    				mp[s[i]]--;
    			}
    		}

    	}

    	int temp=0;
    	for(auto i:mp){
    		if(temp==k) break;
    		if(S>=2){
    			temp+=S/2;
    		}
    		// cout<<F sps S sp;
    	}

    	if(temp<k)
	    	cout<<coin+temp nl;
	    else cout<<coin+k nl;
    }
}

//u 65
//l 97  //dif 32