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

typedef long long Int;
#define REP(i,n) for(int (i)=0;(i)<(int)(n);++(i))

bool ok(string t, int Kr, int Kb) {
	REP(i, t.size()) {
		if (t[i] == 'R') {
			int j = i + Kr;
			if (j < t.size() && t[j] == 'R') return false;
		}
		if (t[i] == 'B') {
			int j = i + Kb;
			if (j < t.size() && t[j] == 'B') return false;
		}
	}
	return true;
}
int main() {
	int Kr, Kb; cin >> Kr >> Kb;
	string s; cin >> s;

	vector<int> pos;
	REP(i, s.size()) if (s[i] == 'R' || s[i] == 'B') {
		pos.push_back(i);
	}

	int ans = 0;
	int n = pos.size();
	REP(st, 1 << n) {
		int rem = 0;
		REP(i, n) if (st >> i & 1) {
			rem |= 1 << pos[i];
		}
		string t;
		REP(i, s.size()) {
			if ((rem >> i & 1) == 0) t += s[i];
		}
		if (ok(t, Kr, Kb)) {
			int cur = t.size();
			ans = max(ans, cur);
		}
	}
	cout << ans << endl;
}