import java.util.Scanner;

public class Main2 {
	public static void main(String[] args) {
		Main2 p = new Main2();
		
	}

	public Main2() {
		Scanner sc = new Scanner(System.in);
		int kr = sc.nextInt();
		int kb = sc.nextInt();
		String s = sc.next();
	
		solve(kr, kb, s);
	}

	public void solve(int kr, int kb, String s) {
		int res = rec(0, kr, kb, new StringBuilder(s));
		System.out.println(res);
		
	}
	
	private int rec(int cur, int kr, int kb, StringBuilder s){
		if(s.length()<=12)
			return 12;
		else if(ok(kr, kb, s))
			return s.length(); 
		else if(cur>=s.length())
			return 0;
		
		StringBuilder sb = new StringBuilder(s);
		int res = 0;
		if(s.charAt(cur)=='W'){
			res = Math.max(res, rec(cur+1, kr, kb, sb));
		}else{
			char c = sb.charAt(cur);
			sb.deleteCharAt(cur);
			res = Math.max(res, rec(cur, kr, kb, sb));
			sb.insert(cur, c);
			res = Math.max(res, rec(cur+1, kr, kb, sb));
		}
		return res;
	}

	private boolean ok(int kr, int kb, StringBuilder s) {
		for(int i=0;i<s.length();i++){
			char c = s.charAt(i);
			if(c=='R' && i+kr<s.length() && s.charAt(i+kr)=='R')
				return false;
			else if(c=='B' && i+kb<s.length() && s.charAt(i+kb)=='B')
				return false;
		}
		
		return true;
	}

}