#include <iostream>
#include <vector>
#include <string>
using namespace std;
#define REP(i, n)           for(int(i)=0;(i)<(n);++(i))

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

void dfs(int i){
    if(i == s.size()){
        maxv = max(maxv, (int)k.size());
        return;
    }
    if(s[i] != 'W') dfs(i+1);

    bool f = false;
    int ks = k.size();
    if(s[i] == 'R' && ( ks-KR < 0 || k[ks-KR] != 'R' ) ){
        k.push_back(s[i]); f = true;
    }
    if(s[i] == 'B' && ( ks-KB < 0 || k[ks-KB] != 'B' ) ){
        k.push_back(s[i]); f = true;
    }
    if(s[i] == 'W'){
        k.push_back(s[i]); f = true;
    }

    if(f){
        dfs(i+1);
        k.pop_back();
    }
}

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