#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp> 
#include <ext/pb_ds/tree_policy.hpp>
 
using namespace __gnu_pbds; 
using namespace std;
 
typedef pair<long long,long long> PLL;
typedef long long LL;
 
#define all(v) v.begin(),v.end()
#define faster {ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);}
#define ordered_multiset tree<int, null_type,less_equal<int>, rb_tree_tag, tree_order_statistics_node_update>    

const LL mod = 1e9 + 7;
const int N = 5000 + 10;
const LL inf = 1e9;

int get(char a, char b, char c){
    int ret = 0;
    ret += ('a' - a + 26) % 26;
    ret += ('b' - b + 26) % 26;
    ret += ('c' - c + 26) % 26;
    return ret;
}

int dp[N][N / 3];

void solve(int test){
    int n, k; cin>>n>>k; k = min(k, n * 26);
    for(int i = 0; i <= n; i++){
        for(int j = 0; j <= n / 3 + 10; j++){
            dp[i][j] = inf;
           
        }
        dp[i][0] = 0;
    }
    
    char s[n + 1];
    for(int i = 1; i <= n; i++) cin>>s[i];

    for(int i = 3; i <= n; i++){
        int cost = get(s[i - 2], s[i - 1], s[i]);
        for(int j = 0; j <= n / 3; j++){
            dp[i][j] = min(dp[i][j], dp[i - 1][j]);
            dp[i][j + 1] = min(dp[i][j + 1], dp[i - 3][j] + cost);
        }
    }
    int ans = 0;
    for(int i = 0; i <= n / 3; i++){
        if(dp[n][i] <= k) ans = i;
    }
    cout<<ans<<'\n';
}

signed main(){
    faster
    int t = 1; 
    cin>>t;
    for(int i = 1; i <= t; i++){
        solve(i);
    }
    return 0;
}