import itertools

R, B = map(int, input().split())
S = input()
ans = 0
for t in itertools.product((0, 1), repeat=20):
    j = 0
    S_new = []
    for s in S:
        if s == 'W':
            S_new.append(s)
        else:
            if t[j]:
                S_new.append(s)
            j += 1
    l = len(S_new)
    for j in range(l):
        if S_new[j] == 'R':
            if (j - R >= 0 and S_new[j - R] == 'R') or (j + R < l and S_new[j + R] == 'R'):
                break
        elif S_new[j] == 'B':
            if (j - B >= 0 and S_new[j - B] == 'B') or (j + B < l and S_new[j + B] == 'B'):
                break
    else:
        ans = max(ans, l)
print(ans)