#line 1 "combinatorial_opt/test/mincostflow.radixheaparray.yuki1288.test.cpp"
#define PROBLEM "https://yukicoder.me/problems/no/1288"
#line 2 "data_structure/radix_heap_array.hpp"
#include <array>
#include <limits>
#include <type_traits>
#include <utility>
#include <vector>

template <class Uint> class radix_heap_array {
    int sz;
    Uint last;
    std::array<std::vector<std::pair<Uint, int>>, std::numeric_limits<Uint>::digits + 1> v;

    struct smallpii {
        unsigned b : 7;
        int j : 25;
    };
    std::vector<smallpii> i2bj;

    template <class U, typename std::enable_if<sizeof(U) == 4>::type* = nullptr>
    static inline unsigned bucket(U x) noexcept {
        return x ? 32 - __builtin_clz(x) : 0;
    }
    template <class U, typename std::enable_if<sizeof(U) == 8>::type* = nullptr>
    static inline unsigned bucket(U x) noexcept {
        return x ? 64 - __builtin_clzll(x) : 0;
    }

    void pull() {
        if (!v[0].empty()) return;
        int b = 1;
        while (v[b].empty()) ++b;
        last = v[b].back().first;
        for (int j = 0; j < int(v[b].size()); j++) last = std::min(last, v[b][j].first);
        for (int j = 0; j < int(v[b].size()); j++) {
            int i = v[b][j].second;
            auto bnxt = bucket(v[b][j].first ^ last);
            i2bj[i] = {bnxt, int(v[bnxt].size())}, v[bnxt].emplace_back(std::move(v[b][j]));
        }
        v[b].clear();
    }

public:
    radix_heap_array() : sz(0), last(0) {}
    bool empty() const noexcept { return sz == 0; }
    int argmin_pop() {
        pull(), --sz;
        int i = v[0].back().second;
        i2bj[i].j = -1;
        v[0].pop_back();
        return i;
    }
    void chmin(Uint vnew, int i) {
        if (i >= int(i2bj.size())) i2bj.resize(i + 1, {0, -1});
        if (i2bj[i].j < 0) {
            auto b = bucket(vnew ^ last);
            ++sz, i2bj[i] = {b, int(v[b].size())}, v[b].emplace_back(vnew, i);
        } else if (v[i2bj[i].b][i2bj[i].j].first > vnew) {
            auto bold = i2bj[i].b, bnew = bucket(vnew ^ last);
            if (bnew < bold) {
                int ilast = v[bold].back().second, j = i2bj[i].j;
                std::swap(v[bold][j], v[bold].back());
                i2bj[ilast].j = j, i2bj[i] = {bnew, int(v[bnew].size())};
                v[bnew].emplace_back(vnew, i), v[bold].pop_back();
            } else {
                v[bold][i2bj[i].j].first = vnew;
            }
        }
    }

    void pop() { argmin_pop(); }
    std::pair<Uint, int> top() { return pull(), v[0].back(); }
    [[deprecated("NOT usual emplace opeation.")]] void emplace(Uint vnew, int i) { chmin(vnew, i); }

    void clear() noexcept { sz = 0, last = 0, i2bj.clear(); }
};
#line 2 "combinatorial_opt/mincostflow_nonegativeloop.hpp"
#include <cassert>
#line 4 "combinatorial_opt/mincostflow_nonegativeloop.hpp"
#include <queue>
#line 6 "combinatorial_opt/mincostflow_nonegativeloop.hpp"

// CUT begin
// Minimum cost flow WITH NO NEGATIVE CYCLE (just negative cost edge is allowed)
// Verified:
// - SRM 770 Div1 Medium https://community.topcoder.com/stat?c=problem_statement&pm=15702
// - CodeChef LTIME98 Ancient Magic https://www.codechef.com/problems/ANCT
template <class Cap = long long, class Cost = long long, Cost INF_COST = std::numeric_limits<Cost>::max() / 2>
struct MinCostFlow {
    struct _edge {
        int to, rev;
        Cap cap;
        Cost cost;
        template <class Ostream> friend Ostream &operator<<(Ostream &os, const _edge &e) {
            return os << '(' << e.to << ',' << e.rev << ',' << e.cap << ',' << e.cost << ')';
        }
    };
    bool _is_dual_infeasible;
    int V;
    std::vector<std::vector<_edge>> g;
    std::vector<Cost> dist;
    std::vector<int> prevv, preve;
    std::vector<Cost> dual; // dual[V]: potential
    std::vector<std::pair<int, int>> pos;

    bool _initialize_dual_dag() {
        std::vector<int> deg_in(V);
        for (int i = 0; i < V; i++) {
            for (const auto &e : g[i]) deg_in[e.to] += (e.cap > 0);
        }
        std::vector<int> st;
        st.reserve(V);
        for (int i = 0; i < V; i++) {
            if (!deg_in[i]) st.push_back(i);
        }
        for (int n = 0; n < V; n++) {
            if (int(st.size()) == n) return false; // Not DAG
            int now = st[n];
            for (const auto &e : g[now]) {
                if (!e.cap) continue;
                deg_in[e.to]--;
                if (deg_in[e.to] == 0) st.push_back(e.to);
                if (dual[e.to] >= dual[now] + e.cost) dual[e.to] = dual[now] + e.cost;
            }
        }
        return true;
    }

    bool _initialize_dual_spfa() { // Find feasible dual's when negative cost edges exist
        dual.assign(V, 0);
        std::queue<int> q;
        std::vector<int> in_queue(V);
        std::vector<int> nvis(V);
        for (int i = 0; i < V; i++) q.push(i), in_queue[i] = true;
        while (q.size()) {
            int now = q.front();
            q.pop(), in_queue[now] = false;
            if (nvis[now] > V) return false; // Negative cycle exists
            nvis[now]++;
            for (const auto &e : g[now]) {
                if (!e.cap) continue;
                if (dual[e.to] > dual[now] + e.cost) {
                    dual[e.to] = dual[now] + e.cost;
                    if (!in_queue[e.to]) in_queue[e.to] = true, q.push(e.to);
                }
            }
        }
        return true;
    }

    bool initialize_dual() {
        return !_is_dual_infeasible or _initialize_dual_dag() or _initialize_dual_spfa();
    }

    template <class heap> void _dijkstra(int s) { // O(ElogV)
        prevv.assign(V, -1);
        preve.assign(V, -1);
        dist.assign(V, INF_COST);
        dist[s] = 0;
        heap q;
        q.emplace(0, s);
        while (!q.empty()) {
            auto p = q.top();
            q.pop();
            int v = p.second;
            if (dist[v] < Cost(p.first)) continue;
            for (int i = 0; i < (int)g[v].size(); i++) {
                _edge &e = g[v][i];
                auto c = dist[v] + e.cost + dual[v] - dual[e.to];
                if (e.cap > 0 and dist[e.to] > c) {
                    dist[e.to] = c, prevv[e.to] = v, preve[e.to] = i;
                    q.emplace(dist[e.to], e.to);
                }
            }
        }
    }

    MinCostFlow(int V = 0) : _is_dual_infeasible(false), V(V), g(V), dual(V, 0) {
        static_assert(INF_COST > 0, "INF_COST must be positive");
    }

    int add_edge(int from, int to, Cap cap, Cost cost) {
        assert(0 <= from and from < V);
        assert(0 <= to and to < V);
        assert(cap >= 0);
        if (cost < 0) _is_dual_infeasible = true;
        pos.emplace_back(from, g[from].size());
        g[from].push_back({to, (int)g[to].size() + (from == to), cap, cost});
        g[to].push_back({from, (int)g[from].size() - 1, (Cap)0, -cost});
        return int(pos.size()) - 1;
    }

    // Flush flow f from s to t. Graph must not have negative cycle.
    using Pque = std::priority_queue<std::pair<Cost, int>, std::vector<std::pair<Cost, int>>, std::greater<std::pair<Cost, int>>>;
    template <class heap = Pque> std::pair<Cap, Cost> flow(int s, int t, const Cap &flow_limit) {
        // You can also use radix_heap<typename std::make_unsigned<Cost>::type, int> as prique
        if (!initialize_dual()) throw; // Fail to find feasible dual
        Cost cost = 0;
        Cap flow_rem = flow_limit;
        while (flow_rem > 0) {
            _dijkstra<heap>(s);
            if (dist[t] == INF_COST) break;
            for (int v = 0; v < V; v++) dual[v] = std::min(dual[v] + dist[v], INF_COST);
            Cap d = flow_rem;
            for (int v = t; v != s; v = prevv[v]) d = std::min(d, g[prevv[v]][preve[v]].cap);
            flow_rem -= d;
            cost += d * (dual[t] - dual[s]);
            for (int v = t; v != s; v = prevv[v]) {
                _edge &e = g[prevv[v]][preve[v]];
                e.cap -= d;
                g[v][e.rev].cap += d;
            }
        }
        return std::make_pair(flow_limit - flow_rem, cost);
    }

    struct edge {
        int from, to;
        Cap cap, flow;
        Cost cost;
        template <class Ostream> friend Ostream &operator<<(Ostream &os, const edge &e) {
            return os << '(' << e.from << "->" << e.to << ',' << e.flow << '/' << e.cap << ",$" << e.cost << ')';
        }
    };

    edge get_edge(int edge_id) const {
        int m = int(pos.size());
        assert(0 <= edge_id and edge_id < m);
        auto _e = g[pos[edge_id].first][pos[edge_id].second];
        auto _re = g[_e.to][_e.rev];
        return {pos[edge_id].first, _e.to, _e.cap + _re.cap, _re.cap, _e.cost};
    }
    std::vector<edge> edges() const {
        std::vector<edge> ret(pos.size());
        for (int i = 0; i < int(pos.size()); i++) ret[i] = get_edge(i);
        return ret;
    }

    template <class Ostream> friend Ostream &operator<<(Ostream &os, const MinCostFlow &mcf) {
        os << "[MinCostFlow]V=" << mcf.V << ":";
        for (int i = 0; i < mcf.V; i++) {
            for (auto &e : mcf.g[i]) os << "\n" << i << "->" << e.to << ":cap" << e.cap << ",$" << e.cost;
        }
        return os;
    }
};
#line 4 "combinatorial_opt/test/mincostflow.radixheaparray.yuki1288.test.cpp"
#include <iostream>
#include <numeric>
#include <string>
#line 8 "combinatorial_opt/test/mincostflow.radixheaparray.yuki1288.test.cpp"
using namespace std;

int main() {
    int N;
    string S;
    cin >> N >> S;
    vector<long long> V(N);
    for (auto &x : V) cin >> x;

    const int s = N * 5, t = s + 1;
    MinCostFlow<int, long long> graph(t + 1);
    for (int d = 0; d < 5; d++) {
        for (int i = 0; i < N - 1; i++) graph.add_edge(d * N + i, d * N + i + 1, N / 4, 0);
    }
    graph.add_edge(s - 1, 0, N / 4, 0);

    for (int i = 0; i < N; i++) {
        int b = 0;
        if (S[i] == 'u') b = N * 1;
        if (S[i] == 'k') b = N * 2;
        if (S[i] == 'i') b = N * 3;
        int fr = b + i + N, to = b + i;
        graph.add_edge(s, fr, 1, 0);
        graph.add_edge(fr, to, 1, V[i]);
        graph.add_edge(to, t, 1, 0);
    }
    auto cost = graph.flow<radix_heap_array<unsigned long long>>(s, t, N).second;
    cout << accumulate(V.begin(), V.end(), 0LL) - cost << '\n';
}