#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
#define rep(i, n) REP(i, 0, n)
#define REP(i, s, e) for (ll i = (s); i < (ll)(e); i++)
#define repr(i, n) REPR(i, n, 0)
#define REPR(i, s, e) for (ll i = (ll)(s - 1); i >= (ll)(e); i--)
#define all(r) r.begin(), r.end()
#define rall(r) r.rbegin(), r.rend()

typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;

template <typename T, typename U>
bool chmax(T& a, const U& b) {
    if (a >= b) return false;
    a = b;
    return true;
}
template <typename T, typename U>
bool chmin(T& a, const U& b) {
    if (a <= b) return false;
    a = b;
    return true;
}

void yes_no(bool f, string yes = "Yes", string no = "No") {
    cout << (f ? yes : no) << "\n";
}

void solve() {
    int r, b;
    cin >> r >> b;
    string s;
    cin >> s;
    int n = s.size();
    vi id(n, -1);
    int cnt_r = 0, cnt_b = 10;
    rep(i, n) {
        if (s[i] == 'R') {
            id[i] = cnt_r++;
        } else if (s[i] == 'B') {
            id[i] = cnt_b++;
        }
    }
    int ans = 0;
    rep(mask, 1 << 20) {
        string t;
        rep(i, n) {
            if (id[i] < 0 || (mask & (1 << id[i]))) t += s[i];
        }
        bool f = true;
        rep(i, t.size()) {
            if (t[i] == 'R') {
                if (i - r >= 0) f &= t[i - r] != 'R';
                if (i + r < t.size()) f &= t[i + r] != 'R';
            }
            if (t[i] == 'B') {
                if (i - b >= 0) f &= t[i - b] != 'B';
                if (i + b < t.size()) f &= t[i + b] != 'B';
            }
        }
        if (f) chmax(ans, (int)t.size());
    }
    cout << ans << "\n";
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int t = 1;
    // cin >> t;
    rep(ti, t) solve();
    return 0;
}