#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <iomanip>
#include <cmath>
#include <stdio.h>
#include <queue>
#include <deque>
#include <cstdio>
#include <set>
#include <map>
#include <bitset>
#include <stack>
#include <cctype>
using namespace std;
int main() {
	int kr, kb;
	cin >> kr >> kb;
	string s;
	cin >> s;
	int ans = 0;
	for (int bit = 0; bit < (1 << 20); bit++) {
		int r = 0, b = 10;
		string s1 = "";
		for (int i = 0; i < 30; i++) {
			if (s[i] == 'R') {
				if (bit & (1 << r)) {
					s1 += 'R';
				}
				r++;
			}
			else if (s[i] == 'B') {
				if (bit & (1 << b)) {
					s1 += 'B';
				}
				b++;
			}
			else if (s[i] == 'W') {
				s1 += 'W';
			}
		}
		bool bo = true;
		for (int i = 0; i < s1.size(); i++) {
			if (s1[i] == 'R' && i - kr >= 0 && s1[i - kr] == 'R') {
				bo = false;
			}
			if (s1[i] == 'B' && i - kb >= 0 && s1[i - kb] == 'B') {
				bo = false;
			}
		}
		if (bo && ans < s1.size()) {
			ans = s1.size();
		}
	}
	cout << ans << endl;
}