KR,KB = list(map(int, input().split(' ')))
S = input()

position = [0 for _ in range(len(S))]
p = 0
for i in range(len(S)):
    if S[i] == 'W':
        position[i] = 21
    else:
        position[i] = p
        p = p + 1

length = 0

# check the removal patterns of 2**20
for i in range(1<<20):
    t = []
    yes = True
    for j in range(len(S)):
        # remove the character at position[j] and check the condition
        if i & (1 << position[j]) == 0:
            t.append(S[j])
            if S[j] == 'R' and KR < len(t) and t[len(t)-KR-1] == 'R':
                yes = False
            if S[j] == 'B' and KB < len(t) and t[len(t)-KB-1] == 'B':
                yes = False

    if yes:
        length = max(length, len(t))

print(length)