#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
using namespace std;

int main(){
    int N, A, B;
    cin >> N >> A >> B;
    string S;
    cin >> S;
    
    vector<int> rle(0);
    int concnt = 0;
    int now_idx = 0;
    while(true){
        if (now_idx >= N - 2){
            if (concnt >= 1){
                rle.push_back(concnt);
            }
            break;
        }
        else if (S.substr(now_idx, 3) == "con"){
            now_idx += 3;
            concnt++;
        }
        else{
            now_idx++;
            if (concnt >= 1){
                rle.push_back(concnt);
            }
            concnt = 0;
        }
    }
    int len = rle.size();
    int INF = N / 3 + 1;
    int MAX_J = N / 6 + 1;
    vector<int> divA(INF);
    for (int i = 0; i < INF; i++){
        divA[i] = i / A;
    }
    vector<int> divB(INF);
    for (int i = 0; i < INF; i++){
        divB[i] = i / B;
    }
    vector<int> dp1(MAX_J, -INF);
    vector<int> dp2(MAX_J, -INF);
    dp1[0] = 0;
    int count = 0;
    for (int i = 0; i < len; i++){
        count += divA[rle[i]];
        for (int j = 0; j <= count; j++){
            for (int k = 0; k <= divA[rle[i]]; k++){
                if (j + k >= MAX_J) continue;
                dp2[j + k] = max(dp2[j + k], dp1[j] + divB[rle[i] - A * k]);
            }
        }
        for (int j = 0; j < MAX_J; j++){
            dp1[j] = dp2[j];
            dp2[j] = -INF;
        }
    }
    int ans = 0;
    for (int j = 0; j < MAX_J; j++){
        if (dp1[j] >= j - 1) ans = max(ans, 2 * j - 1);
        if (dp1[j] >= j) ans = max(ans, 2 * j);
    }
    cout << ans << endl;
}