#include<iostream>
#include<string>
#include<algorithm>
#include<vector>
using namespace std;
int kr,kb;
string s;
int res=0;
int sz;
vector<char> now;
void backtrack(int n){
	if(n==sz){
		res=max(res,(int)now.size());

	}
	else{
		int m=(int)now.size();
		if(sz-n+m<res)return;
		now.push_back(s[n]);
		if(s[n]=='R'){
			if(kr>m||now[m-kr]!='R'){
				backtrack(n+1);
			}
		}
		else if(s[n]=='B'){
			if(kb>m||now[m-kb]!='B')
					backtrack(n+1);
		}
		else backtrack(n+1);
		now.pop_back();
		backtrack(n+1);
	}

}

int main(){
	cin>>kr>>kb>>s;
	sz=(int)s.size();
	now.reserve(sz);
	backtrack(0);
	cout<<res<<endl;
	return 0;

}