#include <bits/stdc++.h>
using namespace std;

int main(void) {
	int Kr, Kb;
	cin >> Kr >> Kb;
	string S;
	cin >> S;
	
	auto dfs = [&](auto &&dfs, string s, int i) ->int {
		int M = s.size();
		if(i == 30) return M;
		if(S[i] == 'W') return dfs(dfs, s + 'W', i + 1);
		
		int ans = dfs(dfs, s, i + 1);
		if(S[i] == 'R' and (M - Kr < 0 or s[M - Kr] != 'R')) ans = max(ans, dfs(dfs, s + 'R', i + 1));
		if(S[i] == 'B' and (M - Kb < 0 or s[M - Kb] != 'B')) ans = max(ans, dfs(dfs, s + 'B', i + 1));
		return ans;
	};
	
	cout << dfs(dfs, "", 0) << endl;
	
	return 0;
}