#include <bits/stdc++.h>
#define rep(i, a) for (int i = 0; i < (a); i++)
#define rep2(i, a, b) for (int i = (a); i < (b); i++)
#define repr(i, a) for (int i = (a) - 1; i >= 0; i--)
#define repr2(i, a, b) for (int i = (b) - 1; i >= (a); i--)
using namespace std;
typedef long long ll;
const ll inf = 1e9;
const ll mod = 1e9 + 9;

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

int dfs(string s) {
	if (dp.count(s)) return dp[s];
	int res = 0;
	bool any = false;
	rep (i, s.length()) {
		if (s[i] == 'R' && i - r >= 0 && s[i - r] == 'R') {
			string n1 = s;
			string n2 = s;
			n1.erase(i - r, 1);
			n2.erase(i, 1);
			res = max(res, dfs(n1));
			res = max(res, dfs(n2));
			any = true;
		}
		if (s[i] == 'R' && i + r < s.length() && s[i + r] == 'R') {
			string n1 = s;
			string n2 = s;
			n1.erase(i + r, 1);
			n2.erase(i, 1);
			res = max(res, dfs(n1));
			res = max(res, dfs(n2));
			any = true;
		}
		if (s[i] == 'B' && i - b >= 0 && s[i - b] == 'B') {
			string n1 = s;
			string n2 = s;
			n1.erase(i - b, 1);
			n2.erase(i, 1);
			res = max(res, dfs(n1));
			res = max(res, dfs(n2));
			any = true;
		}
		if (s[i] == 'B' && i + b < s.length() && s[i + b] == 'B') {
			string n1 = s;
			string n2 = s;
			n1.erase(i + b, 1);
			n2.erase(i, 1);
			res = max(res, dfs(n1));
			res = max(res, dfs(n2));
			any = true;
		}
	}
	if (any) {
		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;
}