#include <iostream>
#include <string>
using namespace std;

int KR,KB,maxv;
string s,k;

void dfs(int i){
    if(i == s.size()){
        maxv = max(maxv, (int)k.size());
        return;
    }
    if(s[i] != 'W') dfs(i+1);
    int ks = k.size();
    if(
        (s[i] == 'R' && ( ks-KR < 0 || k[ks-KR] != 'R' )) ||
        (s[i] == 'B' && ( ks-KB < 0 || k[ks-KB] != 'B' )) || 
        (s[i] == 'W'))
    {
        k.push_back(s[i]);
        dfs(i+1);
        k.pop_back();
    }
}

int main(){
    cin >> KR >> KB >> s;
    dfs(0);
    cout << maxv << endl;
}