#include <string>
#include <vector>
#include <algorithm>
#include <numeric>
#include <set>
#include <map>
#include <queue>
#include <iostream>
#include <sstream>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstring>
#include <cctype>
#include <cassert>
#include <limits>
#include <functional>
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
using namespace std;
typedef vector<int> vi; typedef pair<int,int> pii; typedef vector<pair<int,int> > vpii; typedef long long ll;
template<typename T, typename U> inline void amin(T &x, U y) { if(y < x) x = y; }
template<typename T, typename U> inline void amax(T &x, U y) { if(x < y) x = y; }

int main() {
	int Kr;
	int Kb;
	while(~scanf("%d%d", &Kr, &Kb)) {
		const int K = 10, L = K * 3, M = K * 2;
		char S[L + 1];
		scanf("%s", S);
		string s;
		int ans = 0;
		for(int i = 0; i < 1 << M; ++ i) {
			s.clear();
			int k = 0;
			for(int j = 0; j < L; ++ j) {
				if(S[j] == 'W' || (i >> k ++ & 1))
					s += S[j];
			}
			int n = s.size();
			bool ok = true;
			for(int j = 0; j < n; ++ j) {
				if(s[j] != 'W') {
					int t = s[j] == 'R' ? Kr : Kb;
					if(j + t < n)
						ok &= s[j + t] != s[j];
				}
			}
			if(ok)
				amax(ans, n);
		}
		printf("%d\n", ans);
	}
	return 0;
}