#include <iostream>
#include <vector>
#include <set>
#include <queue>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <fstream>
#include <sstream>
using namespace std;
typedef long long ll;

int Kr, Kb;

bool check(string s){
    for(int i=0;i<s.size();i++){
        if(s[i] == 'W')continue;
        
        if(s[i] == 'R'){
            if(i - Kr >= 0)if(s[i - Kr] == 'R')return false;
            if(i + Kr < s.size())if(s[i + Kr] == 'R')return false;
        } else {
            if(i - Kb >= 0)if(s[i - Kb] == 'B')return false;
            if(i + Kb < s.size())if(s[i + Kb] == 'B')return false;
        }
    }
    
    return true;
}

int main(){
    cin >> Kr >> Kb;
    
    string S;
    cin >> S;
    
    int res = 0;
    for(int r=0;r<1<<10;r++)for(int b=0;b<1<<10;b++){
        int rc = 0;
        int bc = 0;
        
        string s = "";
        for(int i=0;i<S.size();i++){
            if(S[i] == 'W'){
                s += 'W';
                continue;
            }
            
            if(S[i] == 'R'){
                if((r >> rc) & 1){
                    
                } else {
                    s += 'R';
                }
                
                ++rc;
            } else {
                if((b >> bc) & 1){
                    
                } else {
                    s += 'B';
                }
                
                ++bc;
            }
        }
        
        if(check(s)){
            res = max(res, (int)s.size());
        }
    }
    
    cout << res << endl;
    return 0;
}