#include<bits/stdc++.h>
using namespace std;
#include<atcoder/all>
using namespace atcoder;
using ll = long long;
int r,b;
string s;

void solve(){
	int ans  =0;
	for(int bit = 0;bit<(1<<20);bit++){
		string t;
		int j = 0;
		for(int i =0;i<30;i++){
			if(s[i]=='W'){
				t.push_back('W');
			}else{
				if((bit>>j)&1){
					t.push_back(s[i]);
				}
				j++;
			}
		}
		bool is = true;
		for(int i  =0;i<t.size();i++){
			if(t[i]=='W')continue;
			int L = i - (t[i]=='R'?r:b),R = i + (t[i]=='R'?r:b);
			if(L>=0&&L<(int)t.size()){
				if(t[i]==t[L])is = false;
			}
			if(R>=0&&R<(int)t.size()){
				if(t[i]==t[R])is = false;
			}
		}
		if(is)ans = max(ans,(int)t.size());
	}
	cout<<ans<<endl;
}

signed main(){
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	cin >> r >> b;
	cin >> s;
	solve();
}