using System;
using System.IO;
using System.Linq;
using System.Text;
using System.Diagnostics;
using System.Collections.Generic;
using System.Text.RegularExpressions;
using Enu = System.Linq.Enumerable;

class Program
{
    static readonly int Num = 10;

    void Solve()
    {
        int KR = reader.Int(), KB = reader.Int();
        string S = reader.String();
        var RIndex = Enu.Range(0, S.Length).Where(i => S[i] == 'R').ToArray();
        var BIndex = Enu.Range(0, S.Length).Where(i => S[i] == 'B').ToArray();
        int ans = 0;

        for (int RMask = 0; RMask < (1 << Num); RMask++)
            for (int BMask = 0; BMask < (1 << Num); BMask++)
            {
                bool[] remove = new bool[S.Length];
                for (int i = 0; i < Num; i++)
                {
                    if ((RMask >> i & 1) == 1) remove[RIndex[i]] = true;
                    if ((BMask >> i & 1) == 1) remove[BIndex[i]] = true;
                }
                var sb = new StringBuilder();
                for (int i = 0; i < S.Length; i++)
                    if (!remove[i]) sb.Append(S[i]);
                bool ok = true;
                for (int i = 0; i < sb.Length; i++)
                {
                    if (sb[i] == 'R' && i + KR < sb.Length && sb[i + KR] == 'R') ok = false;
                    if (sb[i] == 'B' && i + KB < sb.Length && sb[i + KB] == 'B') ok = false;
                }
                if (ok) ans = Math.Max(ans, sb.Length);
            }

        Console.WriteLine(ans);
    }





    Reader reader = new Reader(Console.In);
    static void Main() { new Program().Solve(); }
}

class Reader
{
    private readonly TextReader reader;
    private readonly char[] separator = { ' ' };
    private readonly StringSplitOptions removeOp = StringSplitOptions.RemoveEmptyEntries;
    private string[] A = new string[0];
    private int i;

    public Reader(TextReader r) { reader = r; }
    public bool HasNext() { return Enqueue(); }
    public string String() { return Dequeue(); }
    public int Int() { return int.Parse(Dequeue()); }
    public long Long() { return long.Parse(Dequeue()); }
    public double Double() { return double.Parse(Dequeue()); }
    public int[] IntLine() { var s = Line(); return s == "" ? new int[0] : Array.ConvertAll(Split(s), int.Parse); }
    public int[] IntArray(int N) { return Enu.Range(0, N).Select(i => Int()).ToArray(); }
    public int[][] IntGrid(int H) { return Enu.Range(0, H).Select(i => IntLine()).ToArray(); }
    public string[] StringArray(int N) { return Enu.Range(0, N).Select(i => Line()).ToArray(); }
    public string Line() { return reader.ReadLine().Trim(); }
    private string[] Split(string s) { return s.Split(separator, removeOp); }
    private bool Enqueue()
    {
        if (i < A.Length) return true;
        string line = reader.ReadLine();
        if (line == null) return false;
        if (line == "") return Enqueue();
        A = Split(line);
        i = 0;
        return true;
    }
    private string Dequeue() { Enqueue(); return A[i++]; }
}