#include <bits/stdc++.h>

using namespace std;

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	int kr, kb;
	string s;
	cin >> kr >> kb >> s;
	vector<int> a;
	for (int i = 0; i < 30; i++) {
		if (s[i] != 'W') a.push_back(i);
	}
	int ans = 0;
	for (int i = 0; i < (1 << 20); i++) {
		vector<int> used(30, true);
		for (int j = 0; j < 20; j++) {
			if (i & (1 << j)) used[a[j]] = false;
		}
		string s1 = "";
		for (int j = 0; j < 30; j++) {
			if (used[j]) s1 += s[j];
		}
		bool flag = true;
		for (int j = 0; j < s1.length(); j++) {
			if (s1[j] == 'W') continue;
			else if (s1[j] == 'R') {
				if (j + kr >= s1.length()) continue;
				if (s1[j + kr] == 'R') {
					flag = false;
					break;
				}
			} else {
				if (j + kb >= s1.length()) continue;
				if (s1[j + kb] == 'B') {
					flag = false;
					break;
				}
			}
		}
		if (flag) ans = max(ans, (int)s1.length());
	}
	cout << ans << endl;
	return 0;
}