from heapq import *
from itertools import *
from functools import *
from collections import *
import sys,math
input = sys.stdin.readline

N,A,B = map(int,input().split())
S = input()[:-1]
S = S.replace('con','X')
X = []
for g,r in groupby(S):
    n = len(list(r))
    if g=='X':
        X.append(n)
if len(X)==0:
    print(0)
    exit()
ans = 0
def segfunc(x, y):
    return min(x,y)

class SegTree:
    """
    Segment Tree
    """

    def __init__(self, init_val, segfunc, ide_ele):
        """
        初期化

        init_val: 配列の初期値
        """
        n = len(init_val)
        self.segfunc = segfunc
        self.ide_ele = ide_ele
        self.num = 1 << (n - 1).bit_length()
        self.tree = [ide_ele] * 2 * self.num
        # 配列の値を葉にセット
        for i in range(n):
            self.tree[self.num + i] = init_val[i]
        # 構築していく
        for i in range(self.num - 1, 0, -1):
            self.tree[i] = segfunc(self.tree[2 * i], self.tree[2 * i + 1])

    def update(self, k, x):
        """
        k番目の値をxに更新

        k: index(0-index)
        x: update value
        """
        k += self.num
        self.tree[k] = x
        while k > 1:
            self.tree[k >> 1] = self.segfunc(self.tree[k], self.tree[k ^ 1])
            k >>= 1

    def query(self, l, r):
        """
        [l, r)のsegfuncしたものを得る

        l: index(0-index)
        r: index(0-index)
        """
        res = self.ide_ele

        l += self.num
        r += self.num
        while l < r:
            if l & 1:
                res = self.segfunc(res, self.tree[l])
                l += 1
            if r & 1:
                res = self.segfunc(res, self.tree[r - 1])
            l >>= 1
            r >>= 1
        return res
INF = (1<<30)
M = max(X)
T = SegTree([(INF,-1) for _ in range(M+1)],min,(INF,-1))
C = Counter(X)
for k,v in C.items():
    T.update(k,(k,v))
# print(X)
for i in range(100000):
    
    if i%2==0:
        # print(k)
        k,v = T.query(A,M+1)
        
        if k==INF:
            print(ans)
            exit()
        if v==1:
            ans += 1
            T.update(k,(INF,-1))
            C[k] -= 1
            C[k-A] += 1
            T.update(k-A,(k-A,C[k-A]))
        else:
            ans += 1
            T.update(k,(k,v-1))
            C[k] -= 1
            C[k-A] += 1
            T.update(k-A,(k-A,C[k-A]))
    else:
        k,v = T.query(B,M+1)
        # print(k)
        if k==INF:
            print(ans)
            exit()
        if v==1:
            ans += 1
            T.update(k,(INF,-1))
            C[k] -= 1
            C[k-B] += 1 
            T.update(k-B,(k-B,C[k-B]))
        else:
            ans += 1
            T.update(k,(k,v-1))       
            C[k] -= 1
            C[k-B] += 1 
            T.update(k-B,(k-B,C[k-B]))