#include <iostream>
#include <iomanip>
#include <vector>
#include <algorithm>
#include <numeric>
#include <functional>
#include <cmath>
#include <queue>
#include <stack>
#include <string>

#define repd(i,a,b) for (int i=(a);i<(b);i++)
#define rep(i,n) repd(i,0,n)
typedef long long ll;

using namespace std;


int inputValue(){
    int a;
    cin >> a;
    return a;
};

void inputArray(int * p, int a){
    rep(i, a){
        cin >> p[i];
    }
};

void inputVector(vector<int> * p, int a){
    rep(i, a){
        int input;
        cin >> input;
        p -> push_back(input);
    }
}

template <typename T>
void output(T a, int precision) {
    if(precision > 0){
        cout << setprecision(precision)  << a << "\n";
    }
    else{
        cout << a << "\n";
    }
}

int kr, kb; // R, B, (W)
string s;
vector <char> t;
int ret = 0;

void dfs(int i){
    if (i == s.size()) {
        ret = max(ret, (int)t.size());
        return;
    }
    
    if (s[i] != 'W') {
        dfs(i + 1);
    }

    bool c = false;
    int sz = (int)t.size();
    
    if (s[i] == 'R' && (sz - kr < 0 || t[sz - kr] != 'R')) {
        t.push_back(s[i]);
        c = true;
    }
    if (s[i] == 'B' && (sz - kb < 0 || t[sz - kb] != 'B')) {
        t.push_back(s[i]);
        c = true;
    }
    if (s[i] == 'W') {
        t.push_back(s[i]);
        c = true;
    }
    
    if (c){
        dfs(i + 1);
        t.pop_back();
    }
    
}

int main(int argc, const char * argv[]) {
    
    // source code
    kr = inputValue();
    kb = inputValue();
    
    cin >> s;
    dfs(0);
    output(ret, 0);
    
    return 0;
}