from heapq import *

n, a, b = map(int, input().split())
S = input()
S = S.replace("con", "*")
lst = []
row = 0
for s in S:
    if s == "*":
        row += 1
    else:
        if row != 0:
            lst.append(row)
        row = 0
if row != 0:
    lst.append(row)
lst.sort()
tot = sum(lst)

aa = 0
bb = 0
C = []
for l in lst:
    bb += l // b
    C.append((-(l % b), l))

heapify(C)

def f(a, b):
    if a > b:
        return 2 * b + 1
    else:
        return 2 * a

ans = f(aa, bb)

while C:

    _, d = heappop(C)
    if d < a:
        continue
    bb -= d // b
    d -= a
    aa += 1
    bb += d // b
    heappush(C, (-(d % b), d))
    ans = max(ans, f(aa, bb))

print(ans)