def dfs(cur, d):
    if d == len(S):
        return len(cur)
        
    if S[d] == 'R':
        if len(cur)-Kr < 0 or cur[len(cur)-Kr] != 'R':
            return max(dfs(cur, d+1), dfs(cur+'R', d+1))
        else:
            return dfs(cur, d+1)
    elif S[d] == 'B':
        if len(cur)-Kb < 0 or cur[len(cur)-Kb] != 'B':
            return max(dfs(cur, d+1), dfs(cur+'B', d+1))
        else:
            return dfs(cur, d+1)
    else:
        return dfs(cur+'W', d+1)

Kr, Kb = map(int, input().split())
S = input()

print(dfs('', 0))