#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <sstream>
#include <cstring>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <numeric>
#include <cctype>
#include <tuple>
#include <array>
#include <climits>
#include <bitset>
#include <cassert>

#ifdef _MSC_VER
#include <agents.h>
#endif

#define FOR(i, a, b) for(int i = (a); i < (int)(b); ++i)
#define rep(i, n) FOR(i, 0, n)
#define ALL(v) v.begin(), v.end()
#define REV(v) v.rbegin(), v.rend()
#define MEMSET(v, s) memset(v, s, sizeof(v))
#define UNIQUE(v) (v).erase(unique(ALL(v)), (v).end())
#define MP make_pair
#define MT make_tuple

using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair<int, int> P;

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);
	cout.setf(ios::fixed);
	cout.precision(20);

	int kr, kb;
	cin >> kr >> kb;
	string s;
	cin >> s;

	int ans = 0;
	rep(i, 1 << 20){
		string t;
		int k = 0;
		rep(j, 30){
			if (s[j] == 'W'){
				t.push_back('W');
				continue;
			}
			if (i >> k & 1) t.push_back(s[j]);
			++k;
		}
		bool ng = false;
		rep(j, t.size()){
			if (t[j] == 'R' && j - kr >= 0 && t[j - kr] == 'R'
				|| t[j] == 'B' && j - kb >= 0 && t[j - kb] == 'B'){
				ng = true;
				break;
			}
		}
		if (!ng) ans = max(ans, (int)t.size());
	}
	cout << ans << endl;
}