#include <bits/stdc++.h>
using namespace std;
const double eps = 1e-9;
const double PI = acos(-1.0);
const long long int mod = 1e9 + 7;
const int MAXN = 1e6 + 5;
void cp() {
  int n, k;
  string s;
  cin >> n >> k >> s;
  vector<pair<int, int> > group;
  int l = 0, r = 0;
  while (l < n) {
    while (l < n && s[l] == 'L') l++;
    if (l >= n) break;
    r = l;
    while (r + 1 < n && s[r + 1] == 'W') r++;
    group.push_back({l, r});
    l = r + 1;
  }
  vector<pair<int, int> > diff;
  for (int i = 0; i < ((int)group.size()) - 1; i++) {
    int d = group[i + 1].first - group[i].second - 1;
    diff.push_back({d, i});
  }
  sort(diff.rbegin(), diff.rend());
  while (k > 0 && !diff.empty()) {
    pair<int, int> last = diff.back();
    diff.pop_back();
    int can = min(last.first, k);
    k -= can;
    for (int i = group[last.second].second + 1;
         i < group[last.second + 1].first && can > 0; i++, can--)
      s[i] = 'W';
  }
  if (k > 0) {
    int pos = -2;
    for (int i = 0; i < n; i++)
      if (s[i] == 'W') pos = i;
    pos++;
    if (pos >= 0 && pos < n)
      for (int i = pos; i < n && k > 0; i++)
        if (s[i] == 'L') s[i] = 'W', k--;
  }
  if (k > 0 && s[0] == 'L') {
    int pos = n;
    for (int i = 0; i < n && pos == n; i++)
      if (s[i] == 'W') pos = i;
    pos--;
    if (pos >= 0) {
      for (int i = pos; i >= 0 && k > 0; i--)
        if (s[i] == 'L') s[i] = 'W', k--;
    }
  }
  int score = 0;
  for (int i = 0; i < n; i++) {
    score += (s[i] == 'W');
    if (i - 1 >= 0 && s[i] == 'W' && s[i - 1] == 'W') score++;
  }
  cout << score << '\n';
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  ;
  int t;
  t = 1;
  cin >> t;
  while (t--) {
    cp();
  }
  return 0;
}
