#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <cstdio>
#include <cmath>
using namespace std;
typedef long long ll;
#define rep(i,n) for(int i=0;i<(n);i++)
const int INF = 1e9;

vector<string> v;

int main(void){
	int kr, kb; cin >> kr >> kb;
	string s; cin >> s;
	for (int mask = 0; mask < (1 << 20); ++mask){
		string tm = "";
		int p = 0;//20bitの位置
		for (int i = 0; i < 30; ++i){
			if(s[i] == 'W'){
				tm += 'W';
			}else{
				if(mask & (1 << p)) tm += s[i];
				p++;
			}
		}
		// cout << tm << endl;
		v.push_back(tm);
	}

	int ans = 0;
	for(auto u : v){
		bool flag = true;
		for (int i = 0; i < u.size(); ++i){
			if(u[i] == 'R'){	
				int idl = i - kr, idr = i + kr;
				if(0 <= idl){
					if(u[idl] == 'R'){
						flag = false;
						break;
					}
				}
				if(idr < u.size()){
					if(u[idr] == 'R'){
						flag = false;
						break;
					}
				}
			}else if(u[i] == 'B'){
				int idl = i - kb, idr = i + kb;
				if(0 <= idl){
					if(u[idl] == 'B'){
						flag = false;
						break;
					}
				}
				if(idr < u.size()){
					if(u[idr] == 'B'){
						flag = false;
						break;
					}
				}
			}
		}
		if(flag){
			// cout << u << endl;
			ans = max(ans, (int)u.size());
		}
	}
	printf("%d\n", ans);
	return 0;
}