N, A, B = map(int, input().split())
S = str(input())
rle = []
concnt = 0
now_idx = 0
while True:
    if now_idx >= N - 2:
        if concnt >= 1:
            rle.append(concnt)
        break
    elif S[now_idx:(now_idx + 3)] == 'con':
        now_idx += 3
        concnt += 1
    else:
        now_idx += 1
        if concnt >= 1:
            rle.append(concnt)
        concnt = 0

INF = N // 3 + 1
MAX_J = (N + 3) // 6 + 1
divA = [i // A for i in range(INF)]
divB = [i // B for i in range(INF)]
dp1 = [-INF for _ in range(MAX_J)]
dp2 = [-INF for _ in range(MAX_J)]
dp1[0] = 0
now = 0
for i in range(len(rle)):
    now += divA[rle[i]]
    for j in range(now + 1):
        for k in range(divA[rle[i]] + 1):
            if j + k >= MAX_J:
                continue
            val = divB[rle[i] - A * k]
            if dp2[j + k] < dp1[j] + val:
                dp2[j + k] = dp1[j] + val
    for j in range(MAX_J):
        dp1[j] = dp2[j]
        dp2[j] = -INF
    #print(dp1[0:5])
ans = 0
for j in range(MAX_J):
    if dp1[j] >= j - 1:
        ans = max(ans, 2 * j - 1)
    if dp1[j] >= j:
        ans = max(ans, 2 * j)
print(ans)