#include <iostream>
#include <vector>
#include <string>
#include <stack>
#include <queue>
#include <cmath>
#include <set>
#include <algorithm>
using namespace std;

int Kr,Kb;
string S;
vector<string>SP;
int mx;

int dfs(string word) {
	if (word.size() <= mx)return 0;
	else if (find(SP.begin(), SP.end(), word) != SP.end())return 0;
	else SP.push_back(word);
	set<int> s;
	queue<int> que;


	for (int i = 0; i < word.size(); i++) {
		if (i + Kr < word.size() && word[i] == 'R'&&word[i + Kr] == 'R') {
			for (int j = i; j <= i + Kr; j++) {
				if (word[j] != 'W') s.insert(j);
			}
		}
		else if (i + Kb < word.size() && word[i] == 'B'&&word[i + Kb] == 'B') {
			for (int j = i; j <= i + Kb; j++) {
				if (word[j] != 'W') s.insert(j);
			}
		}
	}
	if (s.size() == 0) return max(mx, (int)word.size());
	for (auto itr = s.begin(); itr != s.end(); itr++) {
		que.push(*itr);
		//cout << *itr << endl;
	}
	//cout << word << endl;
	while (que.size()) {
		//cout << st.size() << endl;
		string word2 = word;
		int p = que.front(); que.pop();
		//cout << p << endl;
		word2.erase(word2.begin() + p);
		mx = max(mx, dfs(word2));
		//cout << word2 << endl;
		//cout << mx << endl;
	}
	return mx;
}


int main()
{
	cin >> Kr >> Kb;
	cin >> S;

	cout << dfs(S) << endl;

	return 0;
}