#include <bits/stdc++.h>

using namespace std;

int main() {
  int kr, kb;
  string s;
  cin >> kr >> kb >> s;
  set<string> s1{""}, s2;
  for (char c : s) {
    for (auto s : s1) {
      if (c != 'W') s2.insert(s);
      s2.insert(s + c);
    }
    s1 = s2;
    s2.clear();
  }
  int res = 0;
  for (auto s : s1) {
    bool f = true;
    for (int i = 0; i < (int)s.size(); ++i) {
      if (s[i] == 'R') {
        if (0 <= i - kr && s[i - kr] == 'R') f = false;
        if (i + kr < (int)s.size()&& s[i + kr] == 'R') f = false;
      }
      if (s[i] == 'B') {
        if (0 <= i - kb && s[i - kb] == 'B') f = false;
        if (i + kb < (int)s.size()&& s[i + kb] == 'B') f = false;
      }
    }
    if (f) res = max(res, (int)s.size());
  }
  cout << res << endl;
}