#include<cstdio>
#include<vector>


using namespace std;


using s_t=vector<int>;

int kr, kb;


int max_u(int& m, int v)
{
	if(m<v)
	{
		m=v;
		return 1;
	}
	return 0;
}


int check(s_t& s)
{
	int i, n=s.size();

	for(i=0;i<n;i++)
	{
		if(s[i]=='R')
		{
			if(i+kr<n && s[i+kr]=='R') return 0;
		}
		if(s[i]=='B')
		{
			if(i+kb<n && s[i+kb]=='B') return 0;
		}
	}
	return 1;
}


void solve(s_t& s, int& result)
{
	int i, n;

	n=s.size();
	if(n<=result) return;

	if(check(s))
	{
		max_u(result, n);
		return;
	}

	if(n-1<=result) return;

	for(i=0;i<n;i++)
	{
		if(s[i]=='W') continue;
		if(i>0 && s[i]==s[i-1]) continue;
		s_t w;
		w=s;
		w.erase(w.begin()+i);
		solve(w, result);
	}
}


int main(void)
{
	char cs[30+2];
	s_t s;
	int result;

	while(scanf("%d%d%s", &kr, &kb, cs)==3)
	{
		s.clear();
		for(int i=0;cs[i];i++)
		{
			s.push_back(cs[i]);
		}

		result=0;
		solve(s, result);
		printf("%d\n", result);
	}

	return 0;
}