#include <bits/stdc++.h>
using namespace std;
template <typename T>
void tk_input(vector<T> &arr) {
  for (T &i : arr) cin >> i;
}
void solve() {
  int n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  priority_queue<pair<int, int>, vector<pair<int, int> >,
                 greater<pair<int, int> > >
      pq;
  int sc = 0, ls = 0, ls_i = 0, f_i = n, l_i = -1;
  for (int i = 0; i <= n - 1; i++) {
    if (s[i] == 'W') {
      if ((ls > 0) && (f_i != n)) pq.push(pair<int, int>(ls, ls_i));
      f_i = min(f_i, i);
      l_i = max(l_i, i);
      ls_i = i + 1;
      ls = 0;
    } else {
      ls++;
    }
  }
  while ((!pq.empty()) && (k > 0)) {
    auto tp = pq.top();
    pq.pop();
    for (int i = tp.second; i <= tp.first + tp.second - 1; i++) {
      if (k == 0) break;
      s[i] = 'W';
      k--;
    }
  }
  for (int i = f_i - 1; i >= 0; i--) {
    if (k == 0) break;
    s[i] = 'W';
    k--;
  }
  if (l_i != -1) {
    for (int i = l_i + 1; i <= n - 1; i++) {
      if (k == 0) break;
      s[i] = 'W';
      k--;
    }
  }
  sc += (s[0] == 'W');
  for (int i = 1; i <= n - 1; i++) {
    sc += ((s[i] == 'W') * (1 + (s[i - 1] == 'W')));
  }
  cout << sc << '\n';
}
signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int _t;
  cin >> _t;
  while (_t--) solve();
}
