#include<bits/stdc++.h>
namespace {
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-function"
#include<atcoder/all>
#pragma GCC diagnostic pop
using namespace std;
using namespace atcoder;
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; i--)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
template<class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } else return false; }
template<class T> bool chmin(T& a, const T& b) { if (b < a) { a = b; return true; } else return false; }
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;

} int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, a, b;
  cin >> n >> a >> b;
  string s;
  cin >> s;
  VI dpa{0}, dpb, pa, pb;
  for(int i = 0; i < n;) {
    if (s.substr(i, 3) != "con") {
      i++;
      continue;
    }
    int j = i + 3;
    while(s.substr(j, 3) == "con") j += 3;
    int cnt = (j - i) / 3;
    vector<P> ts;
    rep(i, cnt / a + 1) {
      int rest = cnt - i * a;
      int j = rest / b;
      ts.emplace_back(i, j);
    }
    pa = dpa;
    pb = dpb;
    int sza = pa.size(), szb = pb.size();
    rep(i, sza) if (pa[i] != -1) {
      for(auto [x, y]: ts) {
        int ni = i + x, nj = y;
        int mn = min(ni, nj);
        int v = pa[i] + 2 * mn;
        ni -= mn, nj -= mn;
        if (ni) {
          if (ni >= (int)dpa.size()) dpa.resize(ni + 1, -1);
          chmax(dpa[ni], v);
        } else {
          if (nj >= (int)dpb.size()) dpb.resize(nj + 1, -1);
          chmax(dpb[nj], v);
        }
      }
    }
    rep(i, szb) if (pb[i] != -1) {
      for(auto [x, y]: ts) {
        int ni = x, nj = i + y;
        int mn = min(ni, nj);
        int v = pa[i] + 2 * mn;
        ni -= mn, nj -= mn;
        if (ni) {
          if (ni >= (int)dpa.size()) dpa.resize(ni + 1, -1);
          chmax(dpa[ni], v);
        } else {
          if (nj >= (int)dpb.size()) dpb.resize(nj + 1, -1);
          chmax(dpb[nj], v);
        }
      }
    }
    i = j;
  }
  int ans = 0;
  int sza = dpa.size();
  rep(i, sza) chmax(ans, dpa[i] + (i > 0));
  for(int x: dpb) chmax(ans, x);
  cout << ans << '\n';
}