#include<bits/stdc++.h>
using namespace std;
#define int long long
#define endl "\n"
#define ff first
#define ss second
#define pb push_back
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define f(i,x,y) for(int i=x;i<y;i++)
#define f2(i,x,y) for(int i=x;i>=y;i--)
#define pii pair<int,int>
#define Fast ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
const int MOD =1000000007;
const int INF = 1e18;
const int N = 5010;
vector<vector<int>> dp(N,vector<int>(N)),mn_cost(N,vector<int>(3));
void clear(int n){
    for(int i=0;i<=n;i++)
        for(int j=0;j<=n;j++)
            dp[i][j]=-1;
}
int n;
int fun(int ind,int cnt){
    if(cnt==0)return 0;
    if(ind+2>=n)return INF;
    if(dp[ind][cnt]!=-1)return dp[ind][cnt];
    int way1 = fun(ind+1,cnt);
    int way2 = mn_cost[ind][0] + mn_cost[ind+1][1] + mn_cost[ind+2][2] + fun(ind+3,cnt-1);
    return dp[ind][cnt] = min(way1,way2);
}
void solve(int tc){
    int k; cin >> n >> k;
    string s; cin >> s;
    clear(n);
    for(int i=0;i<n;i++){
        for(int j=0;j<3;j++){
            if(s[i]-'a' <= j){
                mn_cost[i][j] = j - (s[i]-'a');
            }
            else {
                mn_cost[i][j] = ('z'-s[i]) + j + 1;
            }
        }
    }
    int i;
    for(i=n;i>=1;i--){
        if(fun(0,i)<=k){
            break;
        }
    }
    cout << i << endl;
}
int32_t main(){

    Fast

    int t=1;

    cin >> t;

    for(int tc=1;tc<=t;tc++){

        solve(tc);
    }
    return 0;
}