#include <bits/stdc++.h>
using namespace std;

#define DUMP(x) cerr << #x << "=" << x << endl
#define DUMP2(x, y) cerr<<"("<<#x<<", "<<#y<<") = ("<<x<<", "<<y<<")"<< endl
#define BINARY(x) static_cast<bitset<16> >(x)

#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define REP(i,m,n) for (int i=m;i<(int)(n);i++)

#define in_range(x, y, w, h) (0<=(int)(x) && (int)(x)<(int)(w) && 0<=(int)(y) && (int)(y)<(int)(h))
#define ALL(a) (a).begin(),(a).end()

typedef long long ll;
const int INF   = 1e9;
const ll  INFLL = 1e18;
typedef pair<int, int> PII;
int dx[4]={0, -1, 1, 0}, dy[4]={-1, 0, 0, 1};

int Kr, Kb;

bool check(string S)
{
    int N = S.size();
    rep(i, N) {
        if (S[i] != 'W') {
            int K = (S[i] == 'R' ? Kr : Kb);
            if (i - K >= 0 && S[i] == S[i - K]) return false;
            if (i + K < N &&  S[i] == S[i + K]) return false;
        }
    }
    return true;
}

int main()
{
    ios::sync_with_stdio(false);

    cin >> Kr >> Kb;
    string S; cin >> S;
    int ans = 0;

    for (int i=0; i<(1<<20); i++) {
        int cnt = 0;
        string tmp;

        for (auto s : S) {
            if (s == 'W') {
                tmp += s;
            } else {
                if (i>>cnt&1) tmp += s;
                cnt++;
            }
        }

        if (check(tmp)) ans = max(ans, (int)tmp.size());
    }
    cout << ans << endl;
}