#include <bits/stdc++.h>
#define GET_MACRO(a, b, c, NAME, ...) NAME
#define rep(...) GET_MACRO(__VA_ARGS__, rep3, rep2)(__VA_ARGS__)
#define rep2(i, a) rep3 (i, 0, a)
#define rep3(i, a, b) for (int i = (a); i < (b); i++)
#define repr(...) GET_MACRO(__VA_ARGS__, repr3, repr2)(__VA_ARGS__)
#define repr2(i, a) repr3 (i, 0, a)
#define repr3(i, a, b) for (int i = (b) - 1; i >= (a); i--)
#define chmin(a, b) ((b) < a && (a = (b), true))
#define chmax(a, b) (a < (b) && (a = (b), true))
using namespace std;
typedef long long ll;

int r, b;
map<string, int> dp;

int dfs(string s) {
	if (dp.count(s)) return dp[s];
	int fr = -1, to = -1;
	rep (i, s.length()) {
		if (s[i] == 'R' && i + r < s.length() && s[i + r] == 'R') {
			fr = i;
			to = i + r;
			break;
		}
		if (s[i] == 'B' && i + b < s.length() && s[i + b] == 'B') {
			fr = i;
			to = i + b;
			break;
		}
	}
	if (fr != -1) {
		int res = 0;
		rep (i, fr, to + 1) if (s[i] != 'W') {
			string t = s;
			t.erase(i, 1);
			chmax(res, dfs(t));
		}
		return dp[s] = res;
	} else {
		return dp[s] = s.length();
	}
}

int main() {
	cin >> r >> b;
	string s;
	cin >> s;
	cout << dfs(s) << endl;

	return 0;
}