#include <bits/stdc++.h>

using namespace std;

int get(char a, char b, char c) {
  int ret = 0;
  if (a != 'a') ret += 'z' - a + 1;
  if (b <= 'b') ret += 'b' - b;
  else ret += 'z' - b + 2;
  if (c <= 'c') ret += 'c' - c;
  else ret += 'z' - c + 3;
  return ret;
}

void solve(int cs) {
  int n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  vector<vector<int>> dp(4, vector<int>(n / 3 + 5, 1e9));
  dp[0][0] = dp[1][0] = dp[2][0] = dp[3][0] = 0;
  int ans = 0;
  for (int i = 2; i < n; i++) {
    for (int j = 0; j <= i / 3 + 1; j++) {
      int ops = get(s[i - 2], s[i - 1], s[i]);
      dp[i % 4][j] = min(dp[i % 4][j], dp[(i - 1 + 4) % 4][j]);
      dp[i % 4][j + 1] = min(dp[i % 4][j + 1], dp[(i - 3 + 4) % 4][j] + ops);
      if (dp[i % 4][j] <= k) {
        ans = max(ans, j);
      }
    }
  }
  cout << ans << "\n";
}

int32_t main() {
  cin.tie(0) -> sync_with_stdio(0);
  int t = 1;
  cin >> t;
  for (int i = 1; i <= t; i++) {
    solve(i);
  }
  return 0;
}