#include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <limits>
#include <climits>
#include <cfloat>
#include <functional>
using namespace std;

int main()
{
    int kr, kb;
    string s;
    cin >> kr >> kb >> s;

    int ret = 0;
    for(int i=0; i<(1<<20); ++i){
        bitset<32> bs(i);
        string t;
        int k = 0;
        for(int j=0; j<30; ++j){
            if(s[j] == 'W'){
                t += 'W';
            }
            else{
                if(bs[k])
                    t += s[j];
                ++ k;
            }
        }

        bool ok = true;
        for(unsigned j=0; j<t.size(); ++j){
            if(t[j] == 'R' && j + kr < t.size() && t[j+kr] == 'R')
                ok = false;
            if(t[j] == 'B' && j + kb < t.size() && t[j+kb] == 'B')
                ok = false;
        }
        if(ok)
            ret = max<int>(ret, t.size());
    }
    cout << ret << endl;

    return 0;
}