#include <bits/stdc++.h>
using namespace std;
using lint = long long;
using pint = pair<int, int>;
using plint = pair<lint, lint>;
struct fast_ios { fast_ios(){ cin.tie(nullptr), ios::sync_with_stdio(false), cout << fixed << setprecision(20); }; } fast_ios_;
#define ALL(x) (x).begin(), (x).end()
#define FOR(i, begin, end) for(int i=(begin),i##_end_=(end);i<i##_end_;i++)
#define IFOR(i, begin, end) for(int i=(end)-1,i##_begin_=(begin);i>=i##_begin_;i--)
#define REP(i, n) FOR(i,0,n)
#define IREP(i, n) IFOR(i,0,n)
template <typename T, typename V>
void ndarray(vector<T>& vec, const V& val, int len) { vec.assign(len, val); }
template <typename T, typename V, typename... Args> void ndarray(vector<T>& vec, const V& val, int len, Args... args) { vec.resize(len), for_each(begin(vec), end(vec), [&](T& v) { ndarray(v, val, args...); }); }
template <typename T> bool chmax(T &m, const T q) { if (m < q) {m = q; return true;} else return false; }
template <typename T> bool chmin(T &m, const T q) { if (m > q) {m = q; return true;} else return false; }
template <typename T1, typename T2> pair<T1, T2> operator+(const pair<T1, T2> &l, const pair<T1, T2> &r) { return make_pair(l.first + r.first, l.second + r.second); }
template <typename T1, typename T2> pair<T1, T2> operator-(const pair<T1, T2> &l, const pair<T1, T2> &r) { return make_pair(l.first - r.first, l.second - r.second); }
template <typename T> vector<T> srtunq(vector<T> vec) { sort(vec.begin(), vec.end()), vec.erase(unique(vec.begin(), vec.end()), vec.end()); return vec; }
template <typename T> istream &operator>>(istream &is, vector<T> &vec) { for (auto &v : vec) is >> v; return is; }
template <typename T> ostream &operator<<(ostream &os, const vector<T> &vec) { os << '['; for (auto v : vec) os << v << ','; os << ']'; return os; }
#if __cplusplus >= 201703L
template <typename... T> istream &operator>>(istream &is, tuple<T...> &tpl) { std::apply([&is](auto &&... args) { ((is >> args), ...);}, tpl); return is; }
template <typename... T> ostream &operator<<(ostream &os, const tuple<T...> &tpl) { std::apply([&os](auto &&... args) { ((os << args << ','), ...);}, tpl); return os; }
#endif
template <typename T> ostream &operator<<(ostream &os, const deque<T> &vec) { os << "deq["; for (auto v : vec) os << v << ','; os << ']'; return os; }
template <typename T> ostream &operator<<(ostream &os, const set<T> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <typename T, typename TH> ostream &operator<<(ostream &os, const unordered_set<T, TH> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <typename T> ostream &operator<<(ostream &os, const multiset<T> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <typename T> ostream &operator<<(ostream &os, const unordered_multiset<T> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &pa) { os << '(' << pa.first << ',' << pa.second << ')'; return os; }
template <typename TK, typename TV> ostream &operator<<(ostream &os, const map<TK, TV> &mp) { os << '{'; for (auto v : mp) os << v.first << "=>" << v.second << ','; os << '}'; return os; }
template <typename TK, typename TV, typename TH> ostream &operator<<(ostream &os, const unordered_map<TK, TV, TH> &mp) { os << '{'; for (auto v : mp) os << v.first << "=>" << v.second << ','; os << '}'; return os; }
#ifdef HITONANODE_LOCAL
#define dbg(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ") " << __FILE__ << endl
#else
#define dbg(x) {}
#endif

constexpr int B = 501;
int main()
{
    int N;
    string S;
    cin >> N >> S;
    vector<lint> V(N);
    cin >> V;
    constexpr lint INF = 1e18;
    vector<vector<lint>> dp[B];
    REP(i3, B) {
        int y = clamp((N - i3 * 3) / 2, 0, B - i3 - 1);
        dp[i3].resize(y + 1);
        REP(i2, dp[i3].size()) {
            int y = N - i3 * 3 - i2 * 2;
            y = clamp(y, 0, B - i3 - i2 - 1);
            dp[i3][i2].resize(y + 1, -INF);
        }
    }
    dp[0][0][0] = 0;

    REP(i, N) {
        if (S[i] == 'y') {
            REP(i3, B) REP(i2, dp[i3].size()) IREP(i1, dp[i3][i2].size() - 1)
            {
                chmax(dp[i3][i2][i1 + 1], dp[i3][i2][i1] + V[i]);
            }
        }
        if (S[i] == 'u') {
            REP(i3, B) IREP(i2, int(dp[i3].size()) - 1) REP(i1, dp[i3][i2].size() - 1)
            {
                chmax(dp[i3][i2 + 1][i1], dp[i3][i2][i1 + 1] + V[i]);
            }
        }
        if (S[i] == 'k') {
            IREP(i3, B - 1) REP(i2, int(dp[i3 + 1].size()) - 1) REP(i1, dp[i3 + 1][i2].size()) {
                chmax(dp[i3 + 1][i2][i1], dp[i3][i2 + 1][i1] + V[i]);
            }
        }
        if (S[i] == 'i') {
            REP(i3, B - 1) REP(i2, int(dp[i3 + 1].size()) - 1) REP(i1, dp[i3 + 1][i2].size()) {
                chmax(dp[i3][i2][i1], dp[i3 + 1][i2][i1] + V[i]);
            }
        }
    }

    cout << dp[0][0][0] << '\n';
}