#include <bits/stdc++.h>
#define endl '\n'
#define F first
#define S second
using namespace std;
#define ll long long
#define pb push_back
#define mod 1000000007
// #define int long long
#define all(x)      x.begin(),x.end()
#define allr(x)     x.rbegin(),x.rend()
#define CheckBit(x,k)   (x & (1LL << k))
#define SetBit(x,k)     (x |= (1LL << k))
#define ClearBit(x,k)   (x &= ~(1LL << k))
#define LSB(mask)       __builtin_ctzll(mask)
#define MSB(mask)       63-__builtin_clzll(mask) 
#define print(x)    cout << #x << " : " << x << endl
#define error1(x)   cerr << #x << " = " << (x) <<endl
#define coutall(v)  for(auto &it: v) cout<<it<<' '; cout<<endl
#define Abid_52     ios::sync_with_stdio(false);cin.tie(0),cin.tie(0)
#define error2(a,b) cerr<<"( "<<#a<<" , "<<#b<<" ) = ( "<<(a)<<" , "<<(b)<<" )\n"
#define UNIQUE(x)   sort(all(x)), x.erase(unique(all(x)), x.end()), x.shrink_to_fit()
template <typename T, typename U> T ceil(T x, U y) {return (x > 0 ? (x + y - 1) / y : x / y);}
template <typename T, typename U> T floor(T x, U y) {return (x > 0 ? x / y : (x - y + 1) / y);}

const int N = 2e5 + 10;
int make_a(char ch){
    if(ch == 'a')return 0;
    return ('z' - ch) + 1;
}
int make_b(char ch){
    if(ch == 'b')return 0;
    return make_a(ch) + 1;
}
int make_c(char ch){
    if(ch == 'c')return 0;
    return make_b(ch) + 1;
}
void solve()
{
    int n, m;
    cin >> n >> m;
    string s;
    cin >> s;
    vector<int>a(n + 5, 0), b(n + 5, 0), c(n + 5, 0);
    for(int i = 0; i < n; i++){
        a[i] = make_a(s[i]);
        b[i] = make_b(s[i]);
        c[i] = make_c(s[i]);
    }
    vector<pair<int,int>>pr;//{cost, index};
    for(int i = 0; i + 2 < n; i++){
        int totCost = make_a(s[i]) + make_b(s[i + 1]) + make_c(s[i + 2]);
        pr.push_back({totCost, i});
    }
    sort(all(pr));
    vector<int>track(n + 1, 0);
    int cnt = 0;
    for(auto it : pr){
        // cout << it.first << " " << it.second << endl;
        if(track[it.second] == 0 && it.first <= m){
            track[it.second] = -1;
            track[it.second + 1] = -1;
            track[it.second + 2] = -1;
            m -= it.first;
            cnt++;
        }
    }
    cout << cnt << endl;
}

int32_t main()
{
    Abid_52;
    int t = 1;
    cin >> t;
    for (int tc = 1; tc <= t; ++tc)
    {
        // cout << "Case " << tc << ": ";
        solve();
    }
}