#include <bits/stdc++.h>

using namespace std;

using int64 = long long;
const int mod = 1e9 + 7;
// const int mod = 998244353;

const int64 infll = (1LL << 62) - 1;
const int inf = (1 << 30) - 1;

struct IoSetup {
  IoSetup() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
    cerr << fixed << setprecision(10);
  }
} iosetup;


template< typename T1, typename T2 >
ostream &operator<<(ostream &os, const pair< T1, T2 > &p) {
  os << p.first << " " << p.second;
  return os;
}

template< typename T1, typename T2 >
istream &operator>>(istream &is, pair< T1, T2 > &p) {
  is >> p.first >> p.second;
  return is;
}

template< typename T >
ostream &operator<<(ostream &os, const vector< T > &v) {
  for(int i = 0; i < (int) v.size(); i++) {
    os << v[i] << (i + 1 != v.size() ? " " : "");
  }
  return os;
}

template< typename T >
istream &operator>>(istream &is, vector< T > &v) {
  for(T &in : v) is >> in;
  return is;
}

template< typename T1, typename T2 >
inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }

template< typename T1, typename T2 >
inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }

template< typename T = int64 >
vector< T > make_v(size_t a) {
  return vector< T >(a);
}

template< typename T, typename... Ts >
auto make_v(size_t a, Ts... ts) {
  return vector< decltype(make_v< T >(ts...)) >(a, make_v< T >(ts...));
}

template< typename T, typename V >
typename enable_if< is_class< T >::value == 0 >::type fill_v(T &t, const V &v) {
  t = v;
}

template< typename T, typename V >
typename enable_if< is_class< T >::value != 0 >::type fill_v(T &t, const V &v) {
  for(auto &e : t) fill_v(e, v);
}

template< typename F >
struct FixPoint : F {
  FixPoint(F &&f) : F(forward< F >(f)) {}

  template< typename... Args >
  decltype(auto) operator()(Args &&... args) const {
    return F::operator()(*this, forward< Args >(args)...);
  }
};

template< typename F >
inline decltype(auto) MFP(F &&f) {
  return FixPoint< F >{forward< F >(f)};
}


int main() {
  int N;
  cin >> N;
  string S;
  cin >> S;
  vector< int > V(N);
  cin >> V;
  unordered_map< int64, int64 > dp;

  auto conv = [&](int64 a, int64 b, int64 c, int64 d) {
    return d * 500 * 500 * 500 + c * 500 * 500 + b * 500 + a;
  };

  auto rec = MFP([&](auto rec, int y, int yu, int yuk, int idx) -> int64 {
    if(idx == N) {
      if(y == 0 && yu == 0 && yuk == 0) return 0;
      else return -infll;
    }
    int beet = conv(y, yu, yuk, idx);
    if(dp.count(beet)) return dp[beet];
    int64 ret = rec(y, yu, yuk, idx + 1);
    if(S[idx] == 'y') {
      if(y < 250) chmax(ret, rec(y + 1, yu, yuk, idx + 1) + V[idx]);
    } else if(S[idx] == 'u') {
      if(y > 0) chmax(ret, rec(y - 1, yu + 1, yuk, idx + 1) + V[idx]);
    } else if(S[idx] == 'k') {
      if(yu > 0) chmax(ret, rec(y, yu - 1, yuk + 1, idx + 1) + V[idx]);
    } else {
      if(yuk > 0) chmax(ret, rec(y, yu, yuk - 1, idx + 1) + V[idx]);
    }
    return dp[beet] = ret;
  });
  cout << rec(0, 0, 0, 0) << "\n";
}