#include <bits/stdc++.h>
using namespace std;
void __print(int x) { cout << x; }
void __print(long x) { cout << x; }
void __print(long long x) { cout << x; }
void __print(unsigned x) { cout << x; }
void __print(unsigned long x) { cout << x; }
void __print(unsigned long long x) { cout << x; }
void __print(float x) { cout << x; }
void __print(double x) { cout << x; }
void __print(long double x) { cout << x; }
void __print(char x) { cout << '\'' << x << '\''; }
void __print(const char *x) { cout << '\"' << x << '\"'; }
void __print(const string &x) { cout << '\"' << x << '\"'; }
void __print(bool x) { cout << (x ? "true" : "false"); }
template <typename T, typename V>
void __print(const pair<T, V> &x) {
  cout << '{';
  __print(x.first);
  cout << ',';
  __print(x.second);
  cout << '}';
}
template <typename T>
void __print(const T &x) {
  int f = 0;
  cout << '{';
  for (auto &i : x) cout << (f++ ? "," : ""), __print(i);
  cout << "}";
}
void _print() { cout << "]" << endl; }
template <typename T, typename... V>
void _print(T t, V... v) {
  __print(t);
  if (sizeof...(v)) cout << ", ";
  _print(v...);
}
template <typename T, typename T1>
T amax(T &a, T1 b) {
  if (b > a) a = b;
  return a;
}
template <typename T, typename T1>
T amin(T &a, T1 b) {
  if (b < a) a = b;
  return a;
}
const int mod = 1e9 + 7;
const int N = 3e5 + 1;
void solve() {
  int n, k;
  string s;
  cin >> n >> k >> s;
  int x = 1;
  bool found = 0;
  vector<string> L;
  string lose = "";
  int cnt = 0, numL = 0;
  for (int i = 0; i < n; i++) {
    cnt += s[i] == 'W';
    numL += s[i] == 'L';
    if (s[i] == 'W' && found && s[i - 1] == 'L') {
      L.push_back(lose);
      lose = "";
    } else if (s[i] == 'W') {
      found = 1;
    } else if (found) {
      lose += 'L';
    }
  }
  int cmp = (L.size() + 1) * found + (!found) * (k > 0);
  sort(L.begin(), L.end());
  for (int i = 0; i < L.size(); i++) {
    string curr = L[i];
    if (curr.size() <= k)
      cnt += curr.size(), cmp--, k -= curr.size(), numL -= curr.size();
    else
      cnt += k, numL -= k, k = 0;
    if (!k) break;
  }
  cnt += min(k, numL);
  cout << cnt * 2 - cmp << "\n";
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int t = 1;
  cin >> t;
  while (t--) solve();
  return 0;
}
